TaxBullUK capital gains tax

Excess reportable income is taxed in a tax year most people would not guess

The rule is six months, and six months moves the charge across the 5 April line more often than not. Across 11,896 published records, 54.1% fall due in a later tax year than the one their reporting period ended in.

The rule

Regulation 94 of SI 2009/3001 treats the excess as an additional distribution, and then fixes the date:

"In these Regulations the 'fund distribution date' for a reporting period of a reporting fund means the date six months following the last day of the reporting period." The Offshore Funds (Tax) Regulations 2009, reg 94(4)

Two consequences that catch people, both straight from the text:

54.1%
land in a later tax year
6,437 of 11,896 records
38
different dates in the year
across 12 calendar months, so there is no ERI season
29.1%
end on a date in December
the single most common month, and still a minority
1.4%
arise between 26 March and 15 April
171 records where a few days moves the whole charge into the other tax year

The six-month shift, measured

Take the most common single period end in the dataset, 2024-12-31 (703 records). That date sits in tax year 2024/25. Six months later is 30 June 2025, which sits in 2025/26. The income is reported on the 2025/26 return, a year after the period most people would file it against, and after the 2024/25 return has already gone in.

Done for every record in the set: 6,437 of 11,896 (54.1%) arise in a later tax year than the one their reporting period ended in, and 5,459 (45.9%) stay in the same one. The later year is the normal outcome.

When reporting periods end, and when the income arises
11,896 records · the arising month is always six months later
Jan: 1 records (0.0%)JanFeb: 573 records (4.8%)FebMar: 1,393 records (11.7%)Mar12%Apr: 12 records (0.1%)AprMay: 1,449 records (12.2%)May12%Jun: 1,112 records (9.3%)Jun9%Jul: 294 records (2.5%)JulAug: 2,419 records (20.3%)Aug20%Sep: 173 records (1.5%)SepOct: 652 records (5.5%)OctNov: 355 records (3.0%)NovDec: 3,463 records (29.1%)Dec29%
Reporting periods end in all twelve months. December is the largest single month at 29.1%, nowhere near a majority, so there is no single date to check and no document season. A fund with a December period end has its income arise in June.
Show all twelve months as a table
Reporting period ends inRecordsShareIncome arises in
January10.0%July
February5734.8%August
March1,39311.7%September
April120.1%October
May1,44912.2%November
June1,1129.3%December
July2942.5%January
August2,41920.3%February
September1731.5%March
October6525.5%April
November3553.0%May
December3,46329.1%June

The 5 April cliff

Because the tax year turns on 5 April, a period end in early October puts the fund distribution date within days of the boundary. 171 records (1.4%) have a fund distribution date between 26 March and 15 April, where a few days' difference in the period end moves the entire charge into the other tax year. The period ends responsible are 2018-09-28, 2019-09-29, 2025-09-30, all of them late-September ends, six months from which lands on top of the line.

A fund that shifts its period end by two days, which is an administrative decision nobody announces to unitholders, moves that income between two returns.

What this means if you hold one of these funds

What this cannot tell you

Method

The fund distribution date for each of the 11,896 records is the period end plus six calendar months, clamped to the last day of the target month where the day does not exist (reg 94(4)). It is the same arithmetic the calculator's engine uses. The tax year of a date is the year beginning 6 April. "Later tax year" compares the tax year of the fund distribution date with the tax year of the period end. Legislative text is quoted from legislation.gov.uk as at 2026-09-22.

96 distinct period-end dates appear, on 38 distinct month-and-day combinations. Every figure in this prose is recomputed from the dataset by test/research-pages.test.mjs.

Related: what the records themselves show, including how often the published figure is nil. To look up a fund, the ERI lookup.