OSS return rejected: error messages in the BZSt portal and what they mean
The portal does not accept your OSS CSV? On an error it imports nothing and offers you an annotated file with the errors in its last column. Here are the causes the BZSt itself names and what you can do before the deadline.
Last updated: 27 October 2026
In brief
- Import: On any error the portal imports no records and offers an annotated CSV for download.
- Known message: "older version of the CSV interface". Check the version line and the UTF-8 encoding.
- Deadline: The BZSt names fixed dates. File early, not on the last day.
How does the import work and where do I see the errors?
You import the CSV in the form "Steuererklärung für die OSS EU-Regelung" in the expandable area "Import von Daten (CSV-Format)". According to the BZSt every file goes through an extensive check. If errors occur, the records are not imported. Instead the portal offers an annotated CSV file for download: its last column lists all errors. After fixing them you repeat the import. After a successful import, compare the number of records in your file with the number imported.
What does "older version of the CSV interface" mean?
This is the message as a user quoted it in a forum in April 2025 (in German): "Ihre CSV-Datei wurde für eine ältere Version der CSV-Schnittstelle erstellt. ... Sind die Versionsangaben korrekt, prüfen Sie bitte das Encoding Ihrer CSV-Datei. Das zulässige Encoding ist UTF-8." In English: your CSV file was created for an older version of the CSV interface; if the version is correct, check the encoding, which must be UTF-8.
This matches what the BZSt writes: on import the portal checks that the file carries the latest version. The version sits in the first line of the file with the prefix #v (for example #v2.0). Two things to check:
- The version line. The version table in the import help shows: version 2.0 changed the encoding from ISO-8859-15 to UTF-8 and no longer allows zero values for tax bases and deviating VAT amounts. Version 1.1 added record type 6 for corrections.
- The encoding. Since the portal update at the end of March 2025 the file must be UTF-8; ISO-8859-15 is no longer supported. The BZSt allows "UTF-8" and "UTF-8 mit BOM". If you built the file by hand, you can re-save it in Windows Notepad ("Editor") via "Save as" with the encoding "UTF-8 mit BOM".
Which version number is current is always in the version table of the import help in the portal. On 27 October 2026 it listed 2.0 as the latest version.
What other causes does the BZSt name?
The import help for the OSS form and the general CSV guide state these rules. Breaking them can make the import fail:
| Rule according to the BZSt | What you check |
|---|---|
| At most 6000 data lines per file | Number of lines |
| Each country may appear only once in record type 1 | Duplicate country lines |
| The VAT amount may deviate by at most 5.00 euros from the calculated amount | Net, rate and VAT amount per line |
| The VAT rate is the percentage of the country of consumption, marked STANDARD or REDUCED | Rate and type per country, especially after a rate change |
| From version 2.0 no zero values for tax base and deviating VAT amounts | Lines with 0.00 |
| The decimal separator is a point (unless the amount is in quotation marks) | Comma instead of point |
| One separator (comma or semicolon) per file, no empty lines | Blank lines at the end |
| Corrections (record type 6): no period before Q3 2021, the corrected amount must differ from the previous one | Correction lines, see Correct an OSS return |
A case from 2024: in the return for the first quarter of 2024, sales to Estonia (22%) and Czechia (12%) were rejected because outdated rates were stored in the portal. A tax firm reported that the BZSt fixed this after their notice and that the errors occurred between 1 and 16 April 2024. So there the fault was not in the seller's file. If an error does not fit your file, ask the hotline below and do not file on the last day.
How do I see the confirmation, and what is the Kassenzeichen?
For the new BZSt online.portal, the BZSt describes: after sending you receive a dispatch confirmation with a data transfer number and the date, and you can download the application with documentation of the transmitted data as a PDF. A red dot on the message icon shows new messages, and you manage your cases under "Meine Vorgänge verwalten". The OSS form itself is in the older BOP at elster.de/bportal; this description comes from the help of the new portal, and the confirmation page in the BOP may look different. Save the confirmation you get in both cases.
The Kassenzeichen is the payment reference the BZSt assigns to you. It comes only after your first filing, with the bank details, and the BZSt tells you in the portal's mailbox. The payment reference of your transfer must carry the Kassenzeichen and the period. Did not get one? First look in the portal mailbox and switch on the notification function. If nothing is there, ask the hotline below. The saved pages do not say how long the BZSt takes. More on paying: OSS payment.
What do I do shortly before the deadline?
The BZSt names the deadlines as fixed dates: 30 April, 31 July, 31 October and 31 January. For the third quarter of 2026 that is 31 October 2026, a Saturday. The BZSt page does not say whether it shifts to the next working day. So plan for Friday, 30 October.
- File early. The hotline for Mein BOP is open Monday to Friday 7:00 to 22:00 and Saturday and Sunday 10:00 to 18:00: 0800 52 35 055. It gives no tax advice.
- Read the errors, do not guess. Download the annotated CSV, fix the named lines, import again.
- Rejected does not mean filed. The CSV import only fills in the form; the return is filed only when you send the form. A file rejected at import has transmitted nothing yet and does not meet any deadline. The return is done only when you hold a confirmation after sending. Missed the deadline? See OSS: missed deadline.
- Do not forget the nil return. The return is due even with no sales: OSS nil return.
How VAT GPT helps
VAT GPT is the tax software for Amazon and eBay sellers in Germany: your OSS return first, then VAT, EÜR, trade tax and income tax, calculated and filed in one place.
- You import your Amazon and eBay CSV reports, VAT GPT sorts the sales by country and creates the OSS file, whose first line is #v2.0.
- You review the country lines before sending.
- With VAT GPT Pro, VAT GPT sends the return to the BZSt for you. VAT GPT shows the Transfer Ticket that the portal returns and stores it; you can copy it.
You handle the OSS registration and the ELSTER certificate yourself. There is Free, Go (30 days free with all Pro features) and Pro. Try for Free Now
Not tax advice: the content does not replace individual advice.
Frequently asked questions
Why was my OSS return rejected? Because of the BZSt file rules, for example: old CSV version, wrong encoding, a calculation deviation over 5.00 euros, duplicate countries. The annotated CSV gives the reason per line.
How do I see that the return arrived? By the confirmation the portal shows after sending (in the new portal with a data transfer number and a PDF). The Kassenzeichen follows in the mailbox.
I got no Kassenzeichen, what now? Check the mailbox and notifications, otherwise call the hotline. See above.
Do I have to change the CSV by hand? If the errors are listed in the annotated file, yes: fix the line and import again. For character problems, re-saving as UTF-8 often does it.
Whom do I call? The hotline for Mein BOP: 0800 52 35 055. More on access: BZSt portal login.