When is the Self Assessment deadline for the 2026/27 tax year?

Full answer

The 2026/27 Self Assessment tax return covers income earned between 6 April 2026 and 5 April 2027. Key deadlines: Paper return: 31 October 2027. Online return: 31 January 2028. Tax payment (balancing payment): 31 January 2028 — this covers any tax owed for 2026/27 that wasn't collected via PAYE or payments on account. Payments on account: if your Self Assessment bill was £1,000 or more in 2025/26, you may need to make advance payments toward your 2026/27 liability. The first payment on account for 2026/27 was due 31 January 2027; the second is due 31 July 2027. Any balancing payment is due 31 January 2028. Register for Self Assessment: if you're new to Self Assessment, you must register by 5 October 2027 (i.e., 5 October following the end of the tax year). Late filing penalties: £100 immediately after the deadline; £10/day after 3 months (capped at £900 over 90 days); additional flat penalties at 6 and 12 months; penalties based on tax owed for returns over 12 months late. Late payment interest: currently Bank of England base rate + 2.5%, compounding daily. For 2026/27 returns, the online service opens on 6 April 2026. Most accountants and tax preparers recommend filing well before January to avoid the rush. HMRC's online service experiences high traffic in January.

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