Exact, to the penny
We use 15 different imaginary taxpayers to exactly match all 4,300 of HMRC's model tax calculations.
Each of these tax calculations are matched to the penny, giving us recognition from HMRC that our tax software is 100% correct.
And, of course, we sit down and re-verify them all with HMRC every year.
Calculations confirmed by HMRC
Watch & learn
We've made 189 videos, explaining every part of 1st Money.
Every feature has a matching video tutorial, so you can get straight to an answer with only one click. In fact, there's one right here...
We've created 1,000 answers to questions about every part of 1st Money.
A search bar is built into the top of every page, so you can search for answers with only one click.
Every developer, twice a day, runs thousands of asserts to test our software. This includes 7,000 tax asserts, and 14,000 system asserts. That's 21,000 in total.
This makes sure that day-to-day software changes don't accidentally break our existing code.
Unit test asserts
Every developer, twice a day, runs 1,500 code checks. These code checks scan the 6,400 files in our codebase, looking for things to improve in the code.
This way, each day's changes are continuously scrubbed clean.