Which tax software does ChatGPT recommend? Our measurement with 116 questions

In short

• Scope: 116 questions, 214 answers from ChatGPT (model gpt-5-nano, with web search, location Germany).
• Most named: ELSTER, WISO, DATEV; 31 different tool names from our list in total.
• VAT GPT: named in 9 of 214 answers, 3 of them for questions without our name; vatgpt.de linked as a source in 5 answers.

How did we measure?

We ask ChatGPT fixed questions through the OpenAI interface (Responses API) with web search switched on and the location set to Germany (Europe/Berlin). This is a test setup, not a look into any person's ChatGPT app.

Origin of the 116 questions: questions about VAT GPT (3), forum questions (15), queries from Google Search Console (17), questions we set ourselves (31), Google "People also ask" (20), search trends (18), questions from videos (12). Each question belongs to exactly one question family (twelve families, see below).

What we count:

• Named: the answer text contains the name. For VAT GPT: "VAT GPT" or "vatgpt".
• Tool names: we search the answer text for a fixed list of 31 names. Names like lexoffice and Lexware Office are counted separately, as ChatGPT writes them.
• Cited: a link in the answer text points to the domain. Consulted: the domain appears among the web search sources.
• Answers per tool: each answer counts at most once, even if the tool appears several times.

What this means for you: the numbers describe exactly this test setup on 29 October 2026; a different wording, a different model or a different day can return different names.

Which tools did ChatGPT name most often across the 214 answers?

The table shows the 15 most named names. 48 answers named no name from our list.

What this means for you: ELSTER (the tax administration's portal, elster.de) leads here; the count says nothing about the quality of any tool.

Which sources did ChatGPT cite most often?

Two views: domains the answer text links to (cited) and domains the web search read (consulted). 187 cited and 563 consulted domains in total; 112 of 214 answers contained at least one link.

Cited (domain, answers):

Consulted (domain, answers):

What this means for you: the links go mainly to tax administration, provider sites and review portals; forums and Wikipedia are read in addition. In this measurement these domains stand most often behind the answers.

Which tools did ChatGPT name per question family?

Per family the six most named names, counted in answers (questions × runs). The VAT GPT row is in every table, even at zero.

Best tax software (18 questions, 36 answers)

Software for marketplace sellers (12 questions, 24 answers)

Software for the OSS return (12 questions, 24 answers)

OSS return: how to (14 questions, 28 answers)

CSV reports from Amazon and eBay (10 questions, 20 answers)

VAT pre-return (Umsatzsteuer-Voranmeldung) (7 questions, 14 answers)

EÜR, income tax, trade tax (5 questions, 10 answers)

Tax registration (5 questions, 10 answers)

Small business owners (Kleinunternehmer) (3 questions, 6 answers)

Questions with provider names (9 questions, 18 answers)

Questions about VAT GPT itself (3 questions, 6 answers)

Questions from search trends (18 questions, 18 answers)

What this means for you: which names appear depends strongly on the question; questions about the OSS return or CSV reports bring other tools than the question about the best tax software.

How often did ChatGPT name our own product?

We are VAT GPT and we run this site, so this number is stated openly: VAT GPT appeared in 9 of 214 answers (questions that already contain the name: 6; all others: 3 of 208). vatgpt.de was linked in 5 answers and appeared among the consulted sources in 14 answers.

For questions without our name, ChatGPT named VAT GPT in 3 answers (3 different questions), by family: CSV reports from Amazon and eBay: 2, Software for marketplace sellers: 1.

What this means for you: as a reader you see the provider of this page in the same grid as all the others; weigh the numbers with that in mind.

How reliable are the numbers?

We asked 98 questions twice (baseline and daily run, same day). For 3 of them, whether VAT GPT was named differed; for 29 of 98 questions the list of named tools was identical.

• One model: gpt-5-nano is a small model; other models and the ChatGPT app may answer differently.
• One region, one day: location Germany, 29 October 2026.
• Our own questions: we chose the questions; they do not cover everything people ask ChatGPT.
• Not in the numbers: a run of 22 questions on another model (gpt-5-mini) and the four attempts in the ChatGPT app, which failed at the login.

What this means for you: read the numbers as an order of magnitude for this test setup, not as a fixed order; we repeat the runs daily and update this page after larger changes.

Frequently asked questions

Which tax software does ChatGPT recommend? In our measurement ChatGPT named ELSTER, WISO and DATEV most often; there is no single recommendation, the names depend on the question.

How often did ChatGPT name VAT GPT? In 9 of 214 answers, 6 of them for questions that already contain the name. The breakdown is above.

Can I recompute the numbers? Yes. Every number on this page is computed by a script from three result files.

Is this a ranking? No. We only count how often a name appeared in answers, with no judgement on quality or price.

Read next

• Best AI tax software in Germany
• Tax software for Amazon and eBay sellers
• OSS return for online sellers

Sources

• OpenAI, documentation of web search in the API
• ELSTER, the tax administration's portal (German)