WinMentor SAF-T D406: How to generate error-free reports for tax authority submission
A practical guide to SAF-T D406 in WinMentor: correct configuration, XML generation, common errors in the official validator, and how to resolve them.
Mihai Istrati — CTO Azuvio · 2026-05-23 · 7 min · ERP & Integrations
SAF-T D406 — The monthly deadline that doesn't forgive
Starting in 2025, SAF-T D406 is mandatory for large and medium taxpayers, extending to small businesses in 2026. WinMentor includes an integrated SAF-T module, but the tax authority validator is ruthless: a single error results in the entire declaration being rejected. Here is what works.
Step 1: Verify your WinMentor version
SAF-T D406 uses an XML schema that is updated annually. Ensure you are running the latest WinMentor version (check under About → Version). Updates via a maintenance contract are mandatory — older versions generate XMLs with deprecated schemas.
Step 2: Initial Configuration
Service → Configuration → SAF-T D406:
Reporting Type: Monthly (or Quarterly, depending on your obligation)
Reporter Tax ID: Your full VAT/Tax ID including the country prefix
Item Nomenclature — NC Code: Fill in the Combined Nomenclature (NC) codes for items involved in intra-community sales / exports. Missing NC codes result in automatic rejection.
Partner Nomenclature — Country: For foreign partners, correctly fill in the ISO code (DE, FR, IT, etc.)
Step 3: Checks before generation
Before clicking «Generate XML», run the following:
1. Chart of Accounts Check — all accounts used during that month must exist in the chart of accounts with an attached SAF-T code.
2. Client/Supplier Check — all partners involved in transactions must have a Tax ID and a complete address.
3. Item Check — all transacted items must have a valid Unit of Measure code (CIUS standard) and an NC code for international transactions.
4. VAT Check — the rates used must be standard (e.g., 19%, 9%, 5%, 0%, or exempt).
Step 4: XML Generation
Reports → SAF-T D406 → Generate:
Select the period (the previous month).
Check all mandatory sections (MasterFiles + GeneralLedgerEntries + SourceDocuments).
For large taxpayers: also include Assets (fixed assets) and Stock (inventory).
Save the XML in a dedicated folder (NOT on the desktop to avoid data loss).
Step 5: Local validation BEFORE submission
Crucial: Validate the XML with DUKIntegrator (the official tax authority utility) BEFORE submitting. If you do not validate locally and submit directly, the tax authority (ANAF) will reject the declaration, and it will appear as «submitted with errors» in the virtual private space (SPV).
1. Download the latest version of DUKIntegrator from the tax authority website.
2. Select the generated XML.
3. Click «Validate».
4. Resolve every error BEFORE proceeding.
Common errors and how to solve them
«TaxCode invalid»: An accounting account without SAF-T mapping in the chart of accounts. Add it in WinMentor → Chart of Accounts → Edit Account → «SAF-T Tax Code» field.
«CustomerSupplierID duplicate»: Two partners in WinMentor share the same Tax ID. Clean up your nomenclature.
«Invalid UnitOfMeasure»: Items with custom UMs (e.g., "piece"). Change to BUC, KG, L according to standard CIUS codes.
«MissingDocumentDate»: An invoice with no date (rare, but happens with old imports). Identify and correct.
«Account not declared in ChartOfAccounts»: You used an account in a manual journal entry without adding it to the chart of accounts. Add it.
«XML size > 200MB»: SAF-T for large firms can exceed the limit. You must split the file by sections or use the WinMentor Enterprise module which optimizes generation.
Step 6: Submission to the Tax Authority
After a successful local validation:
1. Log in to the electronic portal (SPV) with your digital certificate.
2. Declarations → D406 → Add new declaration.
3. Upload the validated XML.
4. Click «Send».
5. Wait for the response (usually <1 hour, up to 24h during peak days).
6. Confirm STATUS = «ACCEPTED» (not just «Processed» — processed means received, but it can still be rejected after verification).
«I want this whole thing automated»
For companies with 500+ monthly transactions, generating and validating SAF-T takes 4-8 hours per month. With Azuvio over WinMentor, the process changes:
Daily pre-validated XML generation (not monthly) — you know in real-time if errors occur.
Auto-fix for simple errors (UM, NC, Tax ID format).
Automatic submission to the tax authority on the first day of the following month.
Instant alerts upon rejection with the identified cause.
Conclusion
SAF-T D406 in WinMentor works reliably if you follow these steps. The trap is incomplete initial configuration — allocate 4-6 hours the first time, then it becomes a 30-minute monthly routine. Never skip the local DUKIntegrator validation step — it is the difference between a successful filing and a tax penalty.