Best OSS Software: Which Tools Calculate and File the OSS Return

OSS software must do two things: calculate VAT per EU country and rate from your sales, and submit the return to the BZSt. Not every tool does both. We compare VAT GPT, the BZSt portal and eight other options; VAT GPT is our own product.

Last updated: 29 October 2026. Statements about other providers come from their own websites, retrieved on 29 October 2026 (quotes translated from German); statements about VAT GPT come from us.

In short

  • Obligation: The OSS return goes electronically to the BZSt, quarterly by 30 April, 31 July, 31 October and 31 January.
  • Calculation: Several tools describe that they calculate OSS VAT; few state whether they also file it.
  • Decision: Check calculation, marketplace import and filing separately.

What must OSS software do?

The OSS return is not an ELSTER return: the BZSt requires it electronically and provides a form in the BZStOnline portal (BZSt). The tax period is the calendar quarter, and the return is due within one month after quarter end (section 18j(4) UStG). A return is also filed when there were no sales (nil return).

Software therefore needs:

  1. Import: read Amazon or eBay reports.
  2. Calculation: sales by EU country and tax rate.
  3. Submission: send to the BZSt, or deliver a result you enter in the portal.
  4. VAT return: OSS sales appear there only as a net amount in box 45.

What this means for you: A tool that only issues OSS invoices does not replace a return. Ask who files.

Comparison: Which software supports the OSS return?

The table states what each provider writes on the page we checked. "Not stated" means the checked page says nothing about it. As of 29 Oct 2026.

ToolOSS per providerFiles with the BZStAmazon/eBay dataPrice per provider
VAT GPTcalculate the OSS return for all EU countriesyes, with Proimport Amazon and eBay CSV reportsFree; Go 30 days free; Pro €49 per month or €444 per year, incl. VAT
BZStOnline portalform for submitting the OSS returnyou enter the values yourselfnot statedcost of filing not stated on the page
Taxdooin the monthly close "incl. BWA, OSS, UStVA, ZM"not stated"Interfaces to Amazon, Shopify, Paypal etc."no price on the page
Amainvoice"calculates the VAT for the correct OSS return"not statedvia API with Seller Central€43 per month up to 200 documents (from 9 Feb 2026)
sevDesk"Create invoices under the OSS scheme"not statedvia the Billbee interfacePlans €0 to €34.90 per month, excl. VAT
Lexware Officenot statednot statedno direct connection; via billbee or easybillS to XL: €7.90 to €32.90 per month, excl. VAT
DATEV Unternehmen onlinenot statednot statednot stated€11.56 per month
WISO MeinBüronot statednot statednot statedBuchhaltung plan €19.90 per month (annual plan, excl. VAT)
Taxfixnot statednot statednot statedBasic from €39.99
Smartsteuernot statednot statednot stated€39.99, payable on submission
Mein ELSTEROSS does not run through ELSTER but through the BZStOnline portalnonot stated"Most tax forms … free of charge"

What this means for you: Taxdoo, Amainvoice and sevDesk describe OSS functions on their pages; VAT GPT also describes filing directly with the BZSt. This is the state of the pages we checked, not a verdict on functions that are not described there.

When which OSS solution fits

  • You want to calculate and file yourself: VAT GPT calculates from marketplace reports and files with Pro to the BZSt.
  • You want OSS as part of ongoing bookkeeping: Taxdoo, Amainvoice or sevDesk describe OSS in their bookkeeping.
  • You have few sales abroad in the EU: The BZSt portal can be enough; you enter the values yourself. A calculation example: OSS calculation example.

What this means for you: The more countries and tax rates in your reports, the more a software calculation pays off.

How VAT GPT helps with the OSS return

  1. Upload: your Amazon or eBay CSV report. The AI reads amounts, countries and tax rates from invoices.
  2. Check: VAT GPT breaks down VAT by EU country and prepares the OSS return. You review it.
  3. Send: with VAT GPT Pro directly to the BZSt.

Try it free. Step by step: OSS return for online sellers and eBay OSS return.

What this means for you: You need your quarterly Amazon or eBay report; the OSS return page covers the deadlines.

Frequently asked questions

Which software can file the OSS return? VAT GPT calculates it and files it with Pro to the BZSt. Other tools describe calculation or OSS invoices on their pages; the table shows what each names.

Can I file the OSS return through ELSTER? No, it is submitted electronically through the BZStOnline portal.

When is the OSS return due? By 30 April, 31 July, 31 October and 31 January of the following year; payment must have reached the federal treasury by then, direct debit is not possible (BZSt).

Do I need OSS software for Amazon and eBay? Not necessarily; the BZSt portal is enough to file. Software helps with the calculation by country and tax rate.

Further reading

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

Sources