Do you need a tax adviser for the OSS return in Germany?

No. The law puts the duties on the business itself: it notifies its participation, sends the tax return every quarter and pays the tax (section 18j UStG). The BZSt describes the scheme for businesses that do this themselves in the BZStOnline portal. A tax adviser (Steuerberater) can take it over, but does not have to. What matters is that you know beforehand what is involved.

Last updated: October 27, 2026

In brief

Filing yourself is allowed. Registration and the return go through the BZStOnline portal, which the business uses itself.
You need three things: a VAT ID, a certificate for the portal (an ELSTER certificate is enough) and the quarter's sales by country and rate.
The work is in the data, not in the form. How much is in Is filing the OSS return difficult?.
A tax adviser pays off in special cases, for example when it is unclear how your sales are classified, you have been excluded, or several years need correcting.
Whoever is not authorised may not help in tax matters on a commercial basis (section 2 StBerG). Check whom you hire.

May I file the OSS return myself?

Yes. Under section 18j(1) UStG the business must notify its participation in the OSS, and under subsection 4 it sends the tax return within one month after each quarter and calculates the tax in it itself. The law names no rule that requires a tax adviser for this.

The BZSt describes the process from the business's side too: it applies for participation electronically with its VAT ID, the application goes through the BZStOnline portal, and in the portal it also sends its tax returns. The Munich tax adviser chamber writes that the scheme lets "taxpayers and their tax advisers" meet the duties centrally. Both ways are intended.

What do you need to do it yourself?

A VAT ID. The BZSt issues it in addition to the tax number; you apply for the scheme giving the VAT ID.
A certificate for the portal. A certificate is required to log in. An existing ELSTER certificate can be used. The BZSt names the easiest way to get one: registering in the ELSTER portal. Where you file the return is explained in OSS return: BZSt portal, not ELSTER.
The quarter's sales. The form asks for the sales per EU country, split by tax rate, in euros, plus corrections for earlier periods.
A way to pay. You transfer the tax yourself, with the payment reference (Kassenzeichen) and the tax period in the reference text. Direct debit is not possible (Paying your OSS return).
Records. You keep records of the sales that let you check the return and the payment. The retention period is ten years.

Step by step

Check the threshold. If your sales to private customers in other EU countries were at most 10,000 euros net in the previous year and do not go above that in the current year, the OSS is not mandatory; as soon as the threshold is exceeded, the destination country applies. More in The 10,000 euro OSS threshold.
Get a certificate and log in to the BZStOnline portal.
Register. You file the registration notice in the portal. It starts, in principle, on the first day of the calendar quarter after you apply. The steps are in OSS registration in Germany.
After quarter end, collect the sales by country and rate.
File by the end of the following month: 30 April, 31 July, 31 October and 31 January. Without sales you still file a nil return.
Pay, so the money has reached the federal treasury by the end of that month.

What do you give a tax adviser if you hire one?

What belongs in the return anyway. The more complete it arrives, the fewer queries and hours (with time billing every quarter hour counts; worked examples in What does a tax adviser charge for an OSS return?):

your VAT ID and, if you are registered already, the earlier returns and the payment reference,
the quarter's sales reports, for example from Amazon and eBay,
the invoices and credit notes, especially refunds that lead to corrections,
a list of the countries you ship to and the rates you charged,
details of warehouses or establishments in other EU countries.

The chamber names as typical extra work collecting the rates of the destination countries and checking the postings. You need not hand that over if you already keep the rates yourself.

When is a tax adviser worth it?

When your case is no longer "plain sales to private customers". Typical reasons:

Mixed sales: sales to businesses and to private customers, services and goods. What belongs in the return is in OSS return: which sales do you report? and OSS and B2B sales.
Warehouse or establishment in another EU country: further duties can arise there, because the special scheme covers only certain sales. More in OSS or local VAT registration.
Exclusion: anyone who repeatedly fails to meet the duties on time is excluded from the scheme (section 18j(6) UStG).
Corrections over several years: corrections within three years after the deadline go into a later return. How that works is in Correct an OSS return; with many quarters and countries help can make sense.
Doubt whether you are in the scheme at all.

It is your decision. Under the tax advice act, tax advisers, lawyers and auditors, among others, may give unrestricted help in tax matters on a commercial basis (section 3 StBerG); others only within the limits the law allows (section 2 StBerG). Whoever offers to file your OSS return for money should be authorised to do so.

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 file the return yourself; VAT GPT takes over the calculation work:

You upload your Amazon and eBay reports as CSV.
VAT GPT breaks the sales down by country and calculates the OSS return for all EU countries. You check the totals per country.
With VAT GPT Pro you send the return to the BZSt. For that you enter your VAT ID and upload your ELSTER certificate; certificate and password are used for this session only and deleted afterwards.

You do the registration with the BZSt and the payment yourself, in the BZStOnline portal and by bank transfer. VAT GPT is not tax advice. There is a Free plan and Go with 30 days free and all Pro features. Try it for free now

Frequently asked questions

Must I have a tax adviser for the OSS return? No. The law obliges the business itself and does not require a tax adviser (section 18j UStG).

Can my tax adviser file the return for me? Yes. The scheme is meant for taxpayers and their tax advisers. Settle beforehand whether the registration is included and how the work is billed.

Do I need an ELSTER certificate? A certificate is required to log in to the BZStOnline portal; an ELSTER certificate can be used. Without one you cannot reach the form.

What if I forget the return? It is due by the end of the month after the quarter. What applies after a missed deadline is in OSS return missed the deadline.

What if I am unsure I did everything right? You can correct mistakes in a later return, within three years after the filing deadline of the quarter concerned.