DATEV Exports in the Car Trade: Complete Posting Logic from Debit and Credit to the Last BU Key

You are building software for the car trade. Everything works: creating vehicles, managing customers, and issuing invoices. Then comes the request that every DMS project eventually encounters:

“We need a DATEV export.”

It cannot be that difficult, you think. A CSV file, a few numbers, and done.

Then you open the DATEV interface specification (EXTF v7.0). 120 columns. A cryptic header. Posting logic that distinguishes between balance-sheet accounting and EÜR, between § 25a and standard VAT, and between the EU and third countries, with different accounts, offsetting entries, and rules for every tax case.

This article presents the complete DATEV posting logic for the car trade. It is not simplified or reduced to one tax case. It reflects the hundreds of hours we invested at Autaxo to get it right, with real posting tables, every tax case, and the mistakes we encountered along the way.

✅ Reviewed by: Julian Alessio Goßen (B.A. Taxation, M.A. Taxation in progress; Autaxo tax architecture) and Leonard Niehaus (CTO; technical implementation of the DATEV interface)

📅 Current as of: February 23, 2026 · First published: February 22, 2026

🔄 Update policy: This article will be updated when the DATEV EXTF specification or relevant tax provisions change. Last reviewed: February 23, 2026.

🧰 Related tools:

• Margin Scheme Check: May I apply § 25a at all?
• § 25a Margin Calculator: Calculate the margin, tax component, and profit
• Check a VAT ID: Validate EU customers and generate PDF evidence
• Invoice Text Generator: Correct wording for each tax case
• Smart Deal Calculator: Simulate purchases and sales, including § 25a, standard VAT, and EU cases

Key Takeaways (TL;DR)

• Balance sheet vs. EÜR determines the entire posting logic: balance-sheet accounting uses inventory accounts plus WE-VK inventory derecognition; EÜR posts vehicle purchases directly as expenses and recognizes them through OPOS on payment.
• § 25a sales use two revenue accounts: 8193/4138 for the total and 8191/4136 for the margin. No BU key is required.
• BU keys are set in only one place: BU 40 for reclassifications involving an intra-Community acquisition. They are not used anywhere else.
• Customer/vendor accounts (OPOS) are standard: customer account = 10000 + customer no., vendor account = 70000 + customer no., and they remain stable across all exports.
• Partial and cash payments create additional open-item settlement entries, cash on hand to customer/vendor account.
• WE-VK is always posted at the net purchase price. Repairs do not increase inventory. It is triggered when the invoice is issued.
• Third-country revenue is posted to 8120/4120 as VAT-exempt revenue, not to the generic sales account.
• EU supplies: The VAT ID, including country prefix, goes in EXTF field 40 (“EU country and VAT ID”), and the EC Sales List is based on the invoice date.
• Three export routes: EXTF/CSV as a backup, BDS via API for postings, and document transfer for PDFs. They can be used in parallel, but automatic document linking is available only with BDS plus document transfer.
• Input VAT on repairs to § 25a vehicles is deductible under § 15 UStG, but it does not reduce the margin.

Short Definition

A DATEV export in the car trade transfers posting data from car dealership software, or a DMS, into the DATEV EXTF format or directly into DATEV Kanzlei-Rechnungswesen through the BDS API. The posting logic distinguishes between balance-sheet accounting, using inventory accounts, WE-VK inventory derecognition, and customer/vendor accounts, and EÜR, where purchases are posted directly as expenses but become effective for EÜR only upon payment and OPOS settlement. EÜR is the Einnahmen-Überschuss-Rechnung, Germany’s cash-basis income surplus statement. Each tax case, including § 25a, standard VAT, an intra-Community supply, and a third-country transaction, requires its own accounts and posting mechanics.

Part 1: Debit and Credit, Which Are Not What You May Think

The most important rule: debit does not mean plus, and credit does not mean minus.

Debit (Soll) and credit (Haben) identify the side of an entry in double-entry bookkeeping, not its sign.

Rule to remember: Asset and expense accounts increase on the debit side. Liability and revenue accounts increase on the credit side. Every journal entry always has a debit side and a credit side.

In the DATEV EXTF Format

According to the DATEV interface specification (posting batch section), DATEV uses single-line journal entries. The S/H indicator in column B refers to the account in column G:

• S = the account in column G is posted to the debit side (Soll)
• H = the account in column G is posted to the credit side (Haben)

The offsetting account in column H is automatically posted to the other side.

Part 2: Three Routes to the Tax Advisor

Autaxo supports three export routes:

1. EXTF/CSV (Posting Batch): Manual Download

An EXTF-compliant CSV file is downloaded. The accounting firm imports it manually into DATEV Kanzlei-Rechnungswesen.

Recommended for: Firms without access to the DATEV Unternehmen online (DUO) API or firms that prefer a manual review.

2. BDS (Belegdaten-Service) via the DATEV Accounting API

A fully automated API push through the DATEV Accounting API: Autaxo generates the EXTF posting batch and transfers it directly to the client’s DATEV accounting system.

Requirement: An OIDC connection using OAuth 2.0 + PKCE in accordance with the DATEV specification to the advisor’s DATEV account.
Recommended for: Businesses that maintain their own accounts and accounting firms using DUO.

3. Document Transfer (Belege Online / Documents API)

In addition to the posting lines, the related PDF invoices are uploaded directly to DATEV Belege Online. This automatically creates a GoBD-compliant link to the supporting document. GoBD refers to Germany’s principles for properly maintaining and storing books, records, and documents in electronic form and for data access.

Which Route Suits Which Dealer?

Autaxo does not use RDS 1.0/2.0 because these interfaces are outdated and are being replaced by the REST API.

Export Routes in Practice: Parallel Use & Document Linking

Can EXTF, BDS, and document transfer be used in parallel?

Yes. Autaxo can generate an EXTF file for an export month as a manual download while also transmitting posting data through BDS and uploading supporting documents through document transfer. Important: In DATEV, the month must effectively be posted only once. When BDS is used, the EXTF file should generally serve only as a backup or preview, not as an additional import.

Are the BDS posting lines identical to the EXTF lines?

Yes. Autaxo generates the same posting batch for BDS as it does for the EXTF export. There are no differences in posting logic. The accounts, amounts, and BU keys are identical.

Document transfer and document linking

Autaxo uses DATEV-compliant document linking so that uploaded PDF invoices are automatically linked to the corresponding postings. This automatic link is created through the combination of BDS and document transfer, because that combination actually sends the PDFs to DATEV. A basic EXTF download without an API upload transmits no PDFs, so it creates no automatic document link.

Part 3: Structure of the EXTF Format

The Header

"EXTF";700;21;"Buchungsstapel";13;20260223120000000;;"RE";"";"";29098;55003;20260101;4;20260101;20261231;"Buchungsstapel";"";1;0;0;"EUR";;"";;;;"03";;;;"";""

Note: The header must be a single line in the EXTF file, with no line break. It may wrap visually in the blog, but it must not wrap in the exported CSV.

The Most Important Posting-Line Fields

Part 4: Balance Sheet vs. EÜR, the Fundamental Difference

Short answer: Balance sheet = inventory account + WE-VK inventory derecognition + customer account; EÜR = direct expense, effective only upon payment/open-item settlement.

The method of determining profit controls the entire posting logic.

Balance-Sheet Accounting

• The purchase is posted to an inventory account, such as 3980.
• The sale is posted through the customer account (10xxx) against the revenue account.
• On sale, an additional WE-VK entry derecognizes inventory by posting the purchases-for-sales account against inventory.
• Revenue and expense are recognized in the period in which performance occurs.

EÜR (Cash-Basis Income Surplus Statement)

• The purchase is posted directly to a purchases account, such as 3200, against the vendor account.
• There are no inventory accounts and no WE-VK inventory derecognition.
• OPOS logic: The entry is recorded but becomes effective for EÜR only on payment, when the open item is settled.
• The sale is also posted through the customer account against the revenue account.

This distinction runs through every case in this article.

WE-VK in Detail: Measurement and Timing

Measurement: In Autaxo, the WE-VK inventory derecognition is always measured at the net purchase price. Repair costs do not increase inventory value. They are recorded as separate expenses and are not included in the WE-VK measurement.

Tax note: For individual margin scheme taxation under § 25a, incidental costs incurred after acquisition, such as repairs, do not reduce the taxable amount under the margin scheme. Input VAT from repair invoices is nevertheless separately deductible under § 15 UStG. UStG is the Umsatzsteuergesetz or German VAT Act. If the difference is negative, the taxable amount is €0.

Timing: Under Autaxo’s balance-sheet logic, WE-VK inventory derecognition is triggered when the sales invoice is issued, not only when payment is received. Inventory is therefore derecognized in the correct period.

Part 4b: OPOS, Customer Accounts & Vendor Accounts, the Autaxo Approach

Autaxo uses OPOS-based open-item accounting through customer and vendor personal subledger accounts. Each customer or supplier receives a customer number when created.

Customer/Vendor Account Logic

For the DATEV export, Autaxo derives the personal subledger accounts deterministically:

This keeps personal subledger accounts stable across all exports. The accounting firm can rely on customer account 10042 always referring to the same customer.

Can a Customer Be Both a Customer Account AND a Vendor Account?

Yes. The same customer can act both as a buyer, through the customer account, and as a seller, through the vendor account, for example in a trade-in. These are two different personal subledger accounts:

• As a customer account, always 10000 + customer number
• As a vendor account, always 70000 + customer number

There is therefore no automatic offset through identical accounts. Offsets, such as applying a €10,000 trade-in against a €25,000 purchase price, are handled in DATEV through corresponding settlement entries.

Partial and Cash Payments (Open-Item Settlement)

Autaxo supports partial payments. When payments are recorded as cash within the deal, Autaxo generates an additional payment entry in the export that settles the open item in part or in full:

Partial-payment example: Invoice for €18,500, customer pays €10,000 in cash → payment line for €10,000; the balance of €8,500 remains open until the next payment is recorded.

Part 5: Account Reference

All accounts relevant to the car trade for all three standard DATEV charts of accounts:

Note for SKR03/04: Inventory subject to standard VAT and § 25a inventory use the same account, 3980 or 1140 respectively. They are separate in SKR51, using 3100 and 3110.

Tip for car dealers: Ask your tax advisor which chart of accounts is right for you. SKR03 is the classic choice, SKR04 follows balance-sheet presentation, and SKR51 is the industry chart of accounts for the German motor trade.

Part 6: All Tax Cases, the Canonical Cases

All examples use SKR03 for balance-sheet accounting and EÜR. For SKR04/SKR51, use the account numbers in the reference table above.

Case 1: § 25a Margin Scheme Taxation (Standard Sale)

Scenario: Purchase price €15,000 from a private individual, sale price €18,500 to a private customer.

Background: Under margin scheme taxation pursuant to § 25a UStG, see also the practical guide, only the margin, meaning sale price minus purchase price, is taxed. The purchase must not have allowed an input VAT deduction, for example because it was from a private individual.

Purchase (balance sheet):

Sale (balance sheet):

Purchase (EÜR):

Sale (EÜR):

No BU key is required. The § 25a accounts 8193/8191 are DATEV automatic accounts that carry the tax logic. DATEV recognizes from the accounts that only the margin is taxed.

VAT calculation: €3,500 margin ÷ 1.19 × 0.19 = €558.82 VAT, embedded in the margin and not shown separately.

Case 2: Standard VAT (Vehicle with Input VAT Deduction)

Scenario: Net purchase price €20,000 plus €3,800 VAT from a dealer; gross sale price €27,000 to a private customer.

Purchase (balance sheet):

Sale (balance sheet):

Purchase (EÜR):

Sale (EÜR):

Case 3: Trade-In (Exchange with Cash Payment)

Scenario: A customer buys vehicle A for €25,000, trades in vehicle B valued at €10,000, and pays €15,000 in cash.

Autaxo creates two separate transactions, which are offset through customer/vendor accounts:

Transaction 1: Sale of vehicle A (§ 25a, balance sheet):

Transaction 2: Purchase of vehicle B (§ 25a, balance sheet):

The €10,000 offset between the customer and vendor accounts is posted by the accounting firm or performed automatically when customer account = vendor account for the same customer.

Case 4: Intra-Community Supply with an Election Not to Apply § 25a

Scenario: A dealer purchases a used vehicle from a private individual for €15,000, making it eligible for § 25a, and sells it to an EU dealer for €18,500. Autaxo automatically proposes the “EU foreign country” tax case.

Background: When margin scheme taxation is applied, the exemption for intra-Community supplies is excluded under § 25a(7), sentence 1 UStG. A dealer that wants to treat the intra-Community supply as VAT-exempt must therefore elect not to apply the margin scheme. This election can be made for each supply under § 25a(8) UStG.

Purchase (balance sheet):

Sale to EU dealer (intra-Community supply, balance sheet):

Populate field 40 (“EU country and VAT ID”) with the complete VAT ID including country prefix, for example FR12345678901. The supply must be reported in the Zusammenfassende Meldung, Germany’s EC Sales List (ZM).

SKR51 special consideration: SKR51 separates the inventory accounts, with 3110 for § 25a and 3100 for standard VAT. Because the posting for the intra-Community sale derecognizes standard-VAT inventory from 3100, SKR51 would require an additional reclassification from 3110 to 3100. Autaxo does not currently automate this reclassification.

Case 5: Third-Country Export, Such as Switzerland or Turkey

Scenario: VAT-exempt export supply to a buyer outside the EU.

Sale (balance sheet):

Evidence under § 6(4) UStG in conjunction with §§ 8-17 UStDV: Export declaration (ATLAS/MRN), freight documents, and confirmation of receipt in the third country. UStDV is the Umsatzsteuer-Durchführungsverordnung or German VAT Implementing Regulation. Field 40 remains blank for third-country customers without a VAT ID.

Important: Account 8120 (SKR03) / 4120 (SKR04) is the third-country revenue account, not the generic sales revenue account. 8120 means “VAT-exempt export,” not “standard sale.”

Deep dive: Vehicle sales to third countries: MRN and proof of export

Case 6: Negative Margin (Loss-Making § 25a Sale)

Scenario: Purchase price €20,000, sale price €18,000. The margin is negative.

Autaxo uses the individual margin method for each vehicle. If the margin is negative, there is no margin reclassification:

Sale (balance sheet):

There is no 8193 → 8191 line because no positive margin exists. In SKR51, account 8112 (§ 25a revenue, negative margin) is used instead to present the loss component separately.

Vehicle trade register: The transaction is shown as a loss, or negative profit. Accounting does not reclassify an amount to the margin account because negative VAT cannot arise. The taxable amount is €0.

Global margin method under § 25a(4) UStG, which offsets all vehicles during a period, is not implemented in Autaxo. Dealers that apply for the global margin method must perform the offset manually in DATEV.

Case 7: Mixed Invoice with a § 25a Vehicle plus Ancillary Services at 19%

Scenario: § 25a vehicle for €18,500 plus an extended warranty for €500 net and registration costs of €200 net on one invoice.

Autaxo creates a separate posting line with its own tax case for each item:

Sale (balance sheet):

Ancillary services, including warranties, registration, and delivery, are exported as separate items with their own tax treatment, not through the § 25a account.

Case 8: Reversal / Credit Note

Scenario: Invoice was issued incorrectly → reversal → new invoice.

For a reversal transaction, the S/H indicator is automatically reversed. All posting lines are mirrored:

Reversal (balance sheet):

The association is made through the EXTF document field 1, which contains the invoice number. A new transaction with the correct data is then created and exported.

Return to inventory: When a sales invoice is reversed, Autaxo automatically returns the vehicle to inventory. The export mirrors all original entries, including reversal of the inventory derecognition by posting inventory against WE-VK. The opposite applies when a purchase invoice is reversed: the vehicle is removed from inventory again.

Partial reversals: Currently not supported. For example, it is not currently possible to reverse only the warranty item on a mixed invoice while leaving the vehicle unchanged. The entire invoice must be reversed and a new invoice subsequently issued. Partial reversals are planned for future versions.

Reversal after BDS transmission: If an invoice already transmitted through BDS is reversed, Autaxo creates a new reversal entry that is included in the next batch transmission. For example, if a March invoice is reversed in April, the reversal entry is sent to the accounting firm in the April batch.

Case 9: When Does a Purchase Become Effective Under EÜR + OPOS?

Scenario: A dealer using EÜR buys a car for €25,000 in December but does not sell it until February.

EÜR applies the cash-in/cash-out principle under § 11 EStG, where EStG means the Einkommensteuergesetz or German Income Tax Act. Autaxo exports the purchase as an OPOS entry using the vendor account:

Important points:

• If the purchase is paid in December, it is a December expense, regardless of the later sale in February.
• OPOS defers the timing of the EÜR effect until payment, not until the sale.
• EÜR does not park the amount in inventory without affecting profit, as balance-sheet accounting would, because that would be balance-sheet logic.

Case 10: Consignment Transaction (In the Pipeline)

Autaxo does not yet treat a true consignment transaction, where the vehicle remains the property of the principal, as a separate posting case. Dealers handling consignments currently enter the vehicle as a purchase and the commission as a separate item:

Case 11: Changing the Tax Case After Invoicing

Scenario: A § 25a invoice was issued, but it is subsequently discovered that standard VAT was required, for example because input VAT was in fact deductible on the purchase.

In Autaxo, the original invoice must be reversed in full, as described in Case 8. A new invoice is then issued with the correct tax case. The corresponding reversal and new entries are included in the next export.

The system does not allow a retroactive “change of tax case” without a reversal. This prevents inconsistent posting balances in DATEV.

Case 12: Input VAT on Repairs to § 25a Vehicles

Scenario: A dealer purchases a § 25a vehicle for €15,000 with no input VAT deduction. The vehicle is then repaired for €500 net plus €95 VAT at 19%.

Input VAT on repair and maintenance invoices is generally deductible under § 15 UStG because it does not arise from the margin-scheme vehicle purchase, but from separate services.

Repair entry (balance sheet):

Important: Repair costs do not increase the purchase price or inventory value. They also do not reduce the § 25a margin, which is the taxable amount. They are pure expenses that reduce profit, while the VAT calculation on the margin remains unchanged.

Autaxo: Repair invoices are recorded as cost items on the vehicle. The 7% or 19% tax rate can be classified manually. Planned enhancements include AI-based tax-rate recognition and freely configurable account mapping in the settings.

Part 7: A BU Key in Only One Place

Short answer: Autaxo uses BU keys only for reclassifications involving an intra-Community acquisition, with BU 40. § 25a sales do not require a BU key because the accounts carry the tax logic.

A widespread misconception is that BU key 40 is mandatory for § 25a sales. That is incorrect when the dedicated § 25a accounts 8193/8191 are used.

Autaxo sets a BU key in exactly one place: BU 40 for the reclassification of an intra-Community acquisition, posting the inventory account against the intra-Community purchases account. All other postings have no BU key.

This prevents system-level conflicts caused by incorrectly assigned BU keys.

Part 8: When Is the EC Sales List Filed?

Short answer: Based on the invoice date or time of supply, not the payment date. This applies equally to EÜR and balance-sheet accounting.

Under § 18a(6) UStG, the Zusammenfassende Meldung, Germany’s EC Sales List (ZM), is based not on the payment date, but on the invoice issue date, or the month following performance if no invoice exists. This applies regardless of whether the dealer uses balance-sheet accounting or EÜR.

The challenge is that for dealers using EÜR, the posting date, meaning payment, often falls in a different month from the EC Sales List reporting period based on the invoice. For balance-sheet taxpayers, advance-payment cutoffs add another issue.

Part 9: Error Catalog, the Top Five DATEV Export Errors

What Autaxo Prevents Proactively

• Required-field validation before EXTF generation: advisor number, client number, SKR, G/L account length, profit determination method, and fiscal-year start must be configured
• Tax-case validation: The tax case for each deal is suggested automatically and must be confirmed
• DATEV client verification after OIDC: Autaxo checks whether the configured client exists in DATEV
• Nonce validation in the OIDC flow to prevent replay attacks

Part 10: What Autaxo Can and Cannot Yet Do

Why Dealers Switch

The pain point with many DMS products is that they handle the sale at an operational level but leave dealers and accounting firms on their own in two areas:

1. Tax-case logic is not enforced → incorrect DATEV cases, reclassifications, and follow-up questions
2. Documentation duties are not managed as a process → risk emerges during a tax audit

Autaxo connects posting logic with compliance workflows. For example, when a vehicle is sold within the EU, Autaxo automatically creates the relevant tasks, including VAT ID validation with an exportable confirmation certificate, proof of arrival, and alternative evidence, and tracks completion for each deal.

“Our dealers save approximately 70% of the time spent preparing their accounting because they can send all purchases and sales to the tax advisor with the click of a button. No printing, sorting, or filing.”

Honest Limitations

• The global margin method under § 25a(4) UStG is not supported; only the individual margin method is supported
• Consignment transactions are not yet a separate posting case
• Partial reversals, meaning the reversal of individual invoice items, are not yet possible and are planned for future versions
• KOST1/KOST2 cost centers are not yet populated in EXTF. SKR51 dealers using cost-center reporting cannot transfer these dimensions automatically
• Repair account mapping is currently manual for 7%/19%. AI-based tax-rate recognition and configurable account mapping are in development
• A cash book for cash transactions is on the roadmap

Part 11: Accounting Firm Setup (DUO Checklist)

To ensure the DATEV export arrives correctly:

1. ✅ Activate DATEV DUO for the client
2. ✅ Enter the advisor number and client number in Autaxo under Settings → Integration → DATEV
3. ✅ Configure the standard chart of accounts (SKR03/04/51) and G/L account length
4. ✅ Set the profit determination method, balance sheet or EÜR, and beginning of the fiscal year
5. ✅ Authorize the DATEV OIDC connection through the OAuth flow using DATEV login

Autaxo provides a two-minute training video that explains the complete DATEV setup step by step.

Checklist: DATEV Exports for Car Dealership Software

Basics

• EXTF format correct, version 700 and data category 21
• Header is one line, with no line break
• SKR configurable as 03/04/51
• Balance sheet vs. EÜR represented correctly

Tax Cases

• § 25a margin scheme taxation, accounts 8193/8191 and no BU key
• Standard VAT, account 8400 and input VAT split for balance-sheet accounting
• VAT-exempt intra-Community supply, account 8125 and VAT ID in field 40
• VAT-exempt third-country export, account 8120 and § 4 no. 1(a) UStG
• Negative margin, no margin split
• Mixed invoices, with separate lines for each tax case

Architecture

• Customer/vendor accounts through OPOS with deterministic account-number logic
• Inventory derecognition through WE-VK for balance-sheet accounting, at the net purchase price and when the invoice is issued
• Partial/cash payments with open-item settlement entries
• Reversal with S/H inversion and automatic return to inventory
• Reversal after BDS transmission included in the following batch
• Input VAT on repairs separately deductible under § 15 UStG
• Validation before export

For Car Dealers: Evaluate Software

When selecting car dealership software, ask these questions:

1. Does it distinguish between balance-sheet accounting and EÜR?
2. Does the software support § 25a and standard VAT and intra-Community supplies and third-country transactions?
3. Does it post through customer/vendor accounts using OPOS?
4. Are the exports reviewed by actual tax advisors?
5. Does it offer an API integration through BDS or only a manual CSV download?

Frequently Asked Questions (FAQ)

What Do Debit and Credit Mean in a DATEV Export?

Debit and credit indicate the side of an entry, not plus or minus. In EXTF, the S/H indicator in column B refers to the account in column G. The offsetting account is automatically posted to the other side.

Which Accounts Are Used for § 25a Margin Scheme Taxation?

Use 8193/4138 for total revenue and 8191/4136 for the margin. The sale price is posted to 8193, and the margin, meaning sale price minus purchase price, is reclassified to 8191. No BU key is required because the accounts carry the tax logic.

Do I Need a BU Key for § 25a?

No, not when the dedicated § 25a accounts 8193/8191 are used. Autaxo uses BU key 40 in only one place: for reclassifications involving an intra-Community acquisition.

What Is the Difference Between Balance-Sheet Accounting and EÜR in a DATEV Export?

Balance sheet: Purchase posted to inventory account 3980; sale through a customer account plus WE-VK inventory derecognition. EÜR: Purchase posted directly to purchases account 3200/3400 against the vendor account, no inventory accounts, and expense recognized only on payment through OPOS.

What Is the EXTF Format?

It is DATEV’s CSV-based exchange format, version 700, using semicolon separators, a standardized header, and more than 120 columns. It is the standard import format for DATEV Kanzlei-Rechnungswesen and DATEV Unternehmen online.

How Are EU Supplies Posted?

Use account 8125 (SKR03) / 4125 (SKR04), VAT-exempt and with no BU key. Enter the VAT ID including country prefix in field 40, “EU country and VAT ID.” File the EC Sales List based on the invoice date.

What Happens When a § 25a Margin Is Negative?

Under the individual margin method for each vehicle, the sale is posted to 8193 for the total, but there is no margin reclassification to 8191 because no positive margin exists. The deal is recorded as a loss in the vehicle trade register. In SKR51, the separate account 8112 is used for negative margins.

How Do Customer and Vendor Accounts Work in Autaxo?

Autaxo uses OPOS-based open-item accounting. Each customer receives a customer number that is converted deterministically into personal subledger accounts: customer account = 10000 + customer no. and vendor account = 70000 + customer no. The same customer can be both a customer account and a vendor account, for example in a trade-in, but these are two different accounts.

Does Autaxo Support Partial Payments?

Yes. Cash payments create an additional payment entry in the export, either cash on hand to customer account or vendor account to cash on hand. A partial payment leaves the balance as an open item.

Can I Reverse an Invoice After BDS Transmission?

Yes. The reversal entry is included in the next batch transmission. For example, if a March invoice is reversed in April, the April batch contains the reversal entry.

Is Input VAT on Repairs to § 25a Vehicles Deductible?

Yes. Input VAT on repair and maintenance invoices is deductible under § 15 UStG. It does not, however, reduce the § 25a margin, meaning the taxable amount. Repair costs are pure expenses.

Machine-Readable Fact Reference

The following table summarizes every tax case with its accounts and special considerations in a compact format optimized for quick extraction and citation.

Customer/Vendor Account Logic (Autaxo)

Balance Sheet vs. EÜR (Quick Reference)

EXTF Header: Required Fields

Additional Resources

Autaxo blog:

• Margin scheme taxation in the car trade (§ 25a): technical guide
• Common VAT mistakes in the used car trade
• Intra-Community supplies: making VAT-exempt sales
• Vehicle sales to third countries: MRN and proof of export
• E-invoicing in the car trade from 2025: ZUGFeRD and DATEV
• GoBD at a car dealership: what tax authorities actually audit

External primary sources:

• EXTF specification in the DATEV Developer Portal: Field definitions, header, and posting batches
• DATEV Accounting API (BDS): Automated posting-data push
• DATEV Documents API (document transfer): Document images in Belege Online
• § 25a UStG, margin scheme taxation (Gesetze im Internet): Statutory text for margin scheme taxation
• § 6a UStG, intra-Community supply: Requirements for a VAT-exempt intra-Community supply
• § 4 no. 1(a)/(b) UStG, VAT exemptions: Export supplies and intra-Community supplies
• § 18a UStG, EC Sales List: ZM reporting obligation and deadlines
• § 11 EStG, cash-in/cash-out principle: Basis for EÜR timing logic
• § 15 UStG, input VAT deduction: Input VAT on repairs under § 25a
• UStH 2023, § 25a margin scheme taxation (BMF): German Federal Ministry of Finance interpretation and administrative guidance
• EC Sales List (Hamburg Chamber of Commerce)

Julian Goßen is CEO of GOBERU Solutions UG and developer of Autaxo, modern car dealership software with an integrated DATEV interface. The technical implementation of the DATEV interface was completed in collaboration with Leonard Niehaus and reviewed by tax advisors specializing in the automotive industry.