Wrong OSS return: who is liable, and what do you do now?

Even if a service provider, a tax adviser or a piece of software prepared the OSS return, the law puts the duty on you as the business. You have to submit the return, work out the tax yourself and pay it (section 18j (4) UStG). If you later find an error, you correct it in a later OSS return and state the quarter concerned; this is possible within three years (section 18j (4) UStG).

Last updated: October 27, 2026

In brief

  • Who is obliged? The business taking part in the OSS (section 18j (4) UStG). The provision makes no exception for returns that a helper prepares for you.
  • What to do? Pin down the error and the quarter, then correct it in a later OSS return. This works up to three years after the last day of the filing deadline.
  • How serious is an error? That depends on what happened. Recklessly understating tax is an administrative offence with a fine of up to 50,000 euros (section 378 AO); whether that fits your case is not something this article decides.
  • And the provider? Whether they are liable to you is a question of your contract, not of tax law. This article says nothing on it.

Who is liable if the OSS return is wrong?

Tax law does not split the duty between you and your helper. For the OSS: the business using the scheme has to submit a return to the BZSt in the prescribed data format, work out the tax for the period itself and pay it by the last day of the following month (section 18j (4) UStG). You are the person obliged.

One more provision also names the helper: section 378 AO names as a possible offender anyone acting "as a taxpayer or in handling the affairs of a taxpayer" who acts recklessly. The law therefore knows both roles: yours and your helper's. What that means in a given case is for the tax office to examine.

Whether your tax adviser or software provider has to answer to you for the error depends on your contracts. That is not a VAT question. Have it clarified if you suffered a loss; this article cannot answer it.

What do you do when you notice the error?

  1. Pin down the error. Which quarter, which country, which rate? Does it affect several quarters?
  2. Check whether too little or too much tax was declared. You correct both the same way. If too little was declared, speed matters: a fine for recklessness is waived only if you correct before you are told that proceedings have been opened and pay the tax within the period set for you (section 378 (3) AO).
  3. Correct it in a later OSS return. The BZSt says: if a return already submitted has to be corrected, the correction is made in a subsequent return; the form has a special section for corrections, broken down by taxation period and EU member state. The law allows this within three years (section 18j (4) UStG). The portal steps are in Correct an OSS return: amending earlier quarters.
  4. Pay any additional tax. If the correction shows more tax, you pay the difference. Where and how is in Paying your OSS VAT return in Germany.
  5. No longer in the OSS? If you have ended participation and already filed the return for the last registered period, you declare corrections directly in the EU countries concerned (BZSt).

What can happen after an error?

That depends on the kind of error. Three provisions matter for you:

  • Correction: You correct an error in an OSS return already submitted in a later return, within three years and stating the period concerned (section 18j (4) UStG).
  • Fine for recklessness: Anyone who recklessly understates tax commits an administrative offence; the fine can be up to 50,000 euros (section 378 (1) and (2) AO).
  • No fine for a timely correction: It is not imposed to the extent that you correct the incorrect statements before you are told that criminal or fine proceedings have been opened. If too little tax has already been paid, you must also pay it within the period set for you (section 378 (3) AO).

Whether your error was reckless is not something this article can judge. For larger amounts or repeated errors, a talk with a tax adviser makes sense. Anyone who repeatedly fails to meet their OSS duties or does not meet them in time is excluded from the scheme (section 18j (6) UStG).

How do you check the next return before you file it?

Take five minutes before the return goes out, whoever prepared it:

  • Countries and rates: Is every country, every rate and the assignment of goods right? Rates change; see EU VAT rate changes: which countries changed in 2025 and 2026?.
  • Totals: Does the total per country match your marketplace reports and invoices?
  • Euro amounts: You state the amounts in the return in euros (BZSt); foreign currencies have to be converted.
  • Credit notes and returns: Are they counted in the right period?

Common mistakes

  • Assuming responsibility passes to the helper. The duty to file and pay stays with you (section 18j (4) UStG).
  • Leaving a recognised error alone. The fine under section 378 AO is waived only if you correct before you are told that proceedings have been opened (section 378 (3) AO).
  • Entering the correction in the wrong quarter. You state the taxation period to be corrected (section 18j (4) UStG).
  • Leaving the check to the helper alone. Software or adviser, spot checks of countries and totals cost little time.

How VAT GPT helps

In VAT GPT the AI reads amounts, countries and tax rates from your invoices; you check and confirm. That does not change the fact that the return stays yours, but you see the figures before anything is sent.

  1. You upload your Amazon and eBay CSV reports and your invoices.
  2. VAT GPT breaks down the VAT for Germany and the EU (OSS) and calculates the OSS return for all EU countries. You check and confirm.
  3. With VAT GPT Pro you send the OSS return to the BZSt.

There is Free (basic functions, free of charge) and Go (30 days free with all Pro features). Try for free now

Not tax advice: the content does not replace individual advice.

Frequently asked questions

Who is liable if my tax adviser filed the OSS return wrongly? Towards the tax authority you remain the person obliged (section 18j (4) UStG). Whether your adviser has to answer to you follows from your contract, not from the VAT Act.

Do I have to correct a wrong OSS return? Yes. You work out and pay the tax yourself (section 18j (4) UStG); you correct an error in a later OSS return, stating the quarter concerned (section 18j (4) UStG; BZSt).

Until when can I correct an OSS return? Corrections made within three years after the last day of the filing deadline are reported with a later return (section 18j (4) UStG).

Will I be fined? Recklessly understating tax is an administrative offence, up to 50,000 euros (section 378 AO). The fine is not imposed to the extent that you correct before you are told that proceedings have been opened and pay any tax underpaid within the period set for you (section 378 (3) AO). Whether that applies to you is for the tax office or an adviser to clarify.

Can I still correct if I am no longer in the OSS? Yes. If you have ended participation and already filed the return for the last registered period, you declare any necessary corrections directly in the EU countries concerned (BZSt).

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