Fig. 01
software
Pooled.
A UK capital-gains engine that applies HMRC share-identification rules exactly, in order, and keeps the working.
Wall label
- Title
- Pooled
- Medium
- [Stack, written like oil on canvas]
- Dimensions
- [Rules encoded] · [Tests] · [Lines]
- Client
- [Client]
- Role
- Design, build, ship
- Status
- In development · 2026
The problem
HMRC does not let you pick which shares you sold. It tells you, in a fixed order, and the order is easy to get wrong.
Disposals are matched first against shares bought the same day, then against shares bought in the thirty days after, and only then against the Section 104 pool at average cost. Each step changes the cost basis of the next.
Retail investors with a few hundred trades a year cannot do this by hand, and a spreadsheet silently breaks the moment a buy lands inside a thirty-day window. The engine had to be exact, and it had to show its working.
Built
1.1
The matching engine
Every disposal walks the three rules in HMRC order and records which acquisition each parcel of shares was matched against.
1.2
The audit trail
Each number on screen links to the entries that produced it, so a figure can be defended line by line.
1.3
The report
A year-end computation laid out the way a return expects it, exportable for an accountant.
In their words
“[A sentence from the client on what changed]”