Cheat sheet

UK tax year key dates and allowances, one page

The UK tax year runs 6 April to 5 April, and most allowances die at the boundary. Verified 2026/27 figures; the trap column is where the money leaks.

Item	2026/27 figure or date	The trap
Tax year	6 April 2026 to 5 April 2027. Allowances reset at midnight on 5 April.	Doing everything on 4 April. The early-bird version (contributing on 6 April) buys a whole year of extra tax-free growth.
ISA allowance	£20,000 across all ISAs. Use it or lose it; no carry forward.	From 6 April 2027, at most £12,000 of it can go into a CASH ISA if you are under 65. Plan large cash-ISA habits now.
Pension annual allowance	£60,000 (including employer contributions), relief at your marginal rate. Carry forward up to three unused years if you were a scheme member.	The taper for high earners and the £100,000 personal-allowance squeeze both change the arithmetic sharply; contributions near those cliffs work hardest.
Capital gains exempt amount	£3,000 of gains tax-free per year, outside wrappers.	It does not carry over, and the 30-day rule stops you selling and instantly rebuying the same asset to bank it.
Dividend allowance	£500 of dividends tax-free outside wrappers.	So small now that any real dividend portfolio outside an ISA is a standing invitation to the taxman. The fix is the wrapper, not the sale.
Personal savings allowance	£1,000 of interest tax-free (basic rate), £500 (higher rate), £0 (additional).	At 4%+ rates, roughly £25,000 of savings maxes the basic allowance. Above that, weigh a cash ISA against the 2027 change.
Self assessment deadlines	Register by 5 October; paper return 31 October; online return and payment 31 January.	31 January is also when higher-rate pension relief gets reclaimed. Miss the return, miss the refund.
Income tax bands (England/Wales/NI)	Personal allowance £12,570; higher rate above £50,270; additional above £125,140.	The allowance tapers away above £100,000, creating a ~60% effective band to £125,140. Pension contributions are the classic repair.

Verified July 2026 against GOV.UK and platform guidance. Scotland sets different income tax bands. One page cannot be personal advice; the point is knowing which lever exists before the deadline eats it.

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Educational information, not financial advice. Figures current as of July 2026 where dated; allowances and rates change, so check the source before acting.