Can I use this data in my own article, app or spreadsheet?

Yes. Every dataset here is published under the Creative Commons Attribution 4.0 licence. You can republish, quote, chart or build on any of it — commercially included — as long as you credit Fableworks HQ and link to the dataset page. You do not need to ask, register or pay.

Where do the figures come from?

All of them come from HMRC — its published guidance, its legal update notice for Making Tax Digital, and its two Tax Information and Impact Notes. Each dataset names its sources, states the date it was compiled, and describes its method. Where a figure is derived rather than published by HMRC — such as the cumulative 2.72 million people in scope, which is the sum of HMRC's three wave estimates — it is flagged as derived in both the page and the JSON.

How often is the data updated?

Each dataset carries the date it was compiled rather than a promise of freshness. HMRC revises its guidance and estimates, so if you are reading long after that date, treat the linked HMRC source as the live answer. We recompile when the underlying HMRC page changes materially.

Why does a tax tools site publish open data?

Because the questions were worth answering properly and nobody had. HMRC publishes the raw material but rarely the answer — it lists recognised software without counting it, and splits the cost of Making Tax Digital across two impact notes without adding them up. Compiling those answers is useful in its own right, and it is how a small site earns the right to be cited.

Open data

Making Tax Digital, in machine-readable form

Q: Is there an API?

There is no API and no key. Each dataset is a static JSON file at a stable URL, and /data/index.json is a machine-readable index of all of them. Fetch them directly. They are served with no cookies and no tracking.

Five original datasets on Making Tax Digital for Income Tax — free, openly licensed, and published as JSON at stable URLs. Each one answers a question HMRC leaves scattered across its own guidance, names the sources it was compiled from, and states the date it was compiled. Use any of it with attribution. No key, no registration, no charge.

CC BY 4.0 — take it, quote it, chart it, ship it

Credit Fableworks HQ and link to the dataset page. That is the whole licence. Commercial use included; you do not need to ask us first.

6 datasets · all CC BY 4.0 · all compiled from named HMRC sources
Dataset	Compiled	Download
MTD software counts HMRC lists recognised products but never counts them, so nobody can say what share of the market lets you keep using a spreadsheet. This counts them.	25 August 2026	JSON 7.3 kB
MTD qualifying income Which income types count towards the threshold, and — the part people get wrong — whether the test is on turnover before expenses or profit after them.	15 August 2026	JSON 7.1 kB
MTD quarterly update categories The line-by-line income and expense categories, by business type, copied verbatim from the legal update notice rather than paraphrased from software marketing.	15 August 2026	JSON 5.9 kB
MTD penalties The points thresholds and late-payment percentages, plus a per-wave onset table HMRC does not publish: the first deadline at which a penalty can actually cost you anything.	15 August 2026	JSON 7.0 kB
MTD scale and cost HMRC splits the wave populations and compliance costs across two impact notes and never adds them up. This does — ~2.72 million people at ~£320 to set up plus ~£110 a year — and flags the total as derived.	16 August 2026	JSON 5.5 kB
MTD filings per year Everyone repeats "four updates a year" — but that is per business. HMRC states each trade, all UK property and all foreign property are separate businesses, and never multiplies it out. This does: two trades plus a rental is 12 updates plus a final declaration a year, not four.	16 August 2026	JSON 6.8 kB

Everything above is compiled from HMRC's published guidance, its legal update notice and its Tax Information and Impact Notes. Each dataset page links its own sources and shows its method.

How to use it

Every dataset is a static JSON file. There is no API, no key and no rate limit — just fetch the file. /data/index.json is a machine-readable index of all six, including each one's source URLs, method, compile date and licence, so a script can discover the lot from a single request.

curl -s https://fableworkshq.com/data/index.json | jq '.datasets[] | {id, data}'

# or straight to one dataset
curl -s https://fableworkshq.com/mtd-impact/data.json | jq '.headline'

If you are writing about MTD and want a figure checked, or you spot one that has aged, the source links on each dataset page are the live answer. We would rather you quoted it accurately than not at all.

What counts as original here

Restating HMRC's rules is not worth publishing — every accountancy firm in the country has done it. Each of these exists because HMRC publishes the raw material but not the answer:

It lists recognised software but never counts it, so nobody could say what share of the market lets you carry on using a spreadsheet. We counted.
It splits the scale and cost of MTD across two impact notes and never totals them. Added up, HMRC's own estimates come to about 2.72 million people at roughly £320 to set up and £110 a year each.
It states the penalty rules but not when they can first bite. The per-wave onset table — the first deadline at which a point can actually cost you — is derived from two HMRC pages and published nowhere else.

Where a figure is ours rather than HMRC's, the data says so. The 2.72 million total is flagged as derived everywhere it appears, in the page, in the JSON and in the caveats.

Questions

Can I use this commercially?

Yes. CC BY 4.0 permits commercial use. Credit Fableworks HQ and link to the dataset page.

Will the URLs change?

No. The dataset URLs are stable and we intend to keep them that way — a citable dataset that moves is not citable. If a dataset is ever superseded, the old URL will keep serving and say so.

Do you track who downloads it?

No cookies, no analytics scripts, no tracking on these files. Server logs only.

Can you compile something else?

If it is an MTD or UK small-business tax question where HMRC publishes the raw material but not the answer, quite possibly. That is the whole test we apply to ourselves.

Who makes this

Fableworks HQ publishes free tax and Making Tax Digital tools for UK sole traders, landlords and the bookkeepers who look after them — am I in MTD?, every MTD deadline, and around fifty calculators. The datasets are a by-product of building those properly.

We also sell a small number of MTD-ready spreadsheets — a practice tracker for bookkeepers with clients across the three mandation waves, and a toolkit for individuals. The data above is free either way and always will be.