Tax Planning: UK Tax Year End — Key Dates and Deadlines for 2026/27
£20,000. That is how much you can still put into a Cash ISA in the 2026/27 tax year — and it is the last time you will be able to. From 6 April 2027 the cash component drops to £12,000 for anyone under 65, a 40% cut to an allowance that has quietly underpinned British saving for a generation. Anyone treating 2026/27 as just another tax year is about to leave £8,000 of tax-free capacity on the table. The 2026/27 tax year runs from 6 April 2026 to 5 April 2027, and on the surface nothing moved: the personal allowance stayed frozen at £12,570, the basic-rate band at £37,700, and headline income tax rates are unchanged. Beneath that surface, three things already have moved. Dividend tax rose to 10.75% at the basic rate and 35.75% at the higher rate on 6 April 2026. Capital gains tax is now a flat 18%/24% on every chargeable asset. And the cash ISA cut is less than seven months away. This guide sets out every key date, allowance and threshold for 2026/27, with a prioritised checklist you can act on now rather than in the March 2027 panic. Figures are drawn from gov.uk and HMRC's published rates, with the Bank of England base rate at 3.75% (unchanged since December 2025) and CPI at 2.8% in the latest ONS reading.