Fiscari API: UK tax research API for software teams
Last updated: November 3, 2026
In short: Fiscari’s API is a UK tax research API for fintech and accounting software: send a tax question, get a JSON answer cited to legislation or the HMRC manual paragraph. Fiscari is built by Glasscubes. You can try the API free for 50 queries over 30 days, with no credit card.
What the API returns
Send a tax question to POST /v1/query and you get an answer and a list of citations. Each citation gives the source, the section or paragraph, and a link to the official publication. A second endpoint, /v1/query/stream, streams the answer as it is written, so you can show it to your users token by token.
The final message of a streamed answer also carries a confidence rating (high, medium, low or none), the share of claims covered by citations, and any warnings.
What it answers from
The same UK government sources as the Fiscari app: UK legislation, HMRC manuals, VAT notices, Revenue & Customs Briefs, tribunal decisions and GOV.UK guidance. See how Fiscari finds and cites its sources.
When it can’t cite a source
Fiscari declines to answer rather than guess. You are charged only for answers that are grounded in an official source: a refused question is not billed.
Free trial and cost
- Free trial: 50 queries over 30 days, no credit card, enough to build and test an integration.
- After the trial: pay as you go. There is no ongoing free tier for the API.
- How it is charged: by usage, with the cost of each query returned in the response headers. The current rates are in the API documentation.
The free account in the Fiscari app, for people asking questions rather than building software, is separate: see the free tier.
Get started
- Read the API documentation.
- Create an account and an API key.
- Send your first question and check the citations it returns.