What is tax week 53 and does it affect how much tax I pay?

Full answer

Because the UK tax year runs from 6 April to 5 April (365 or 366 days) but most weekly-paid employees are paid on a fixed weekly cycle, the calendar occasionally does not divide neatly into exactly 52 weekly pay days -- in some years there is an extra, 53rd weekly payday (or, less commonly, a 27th fortnightly payday or a 14th four-weekly payday) falling within the tax year. **Why it happens** 52 weeks of 7 days is 364 days, one or two days short of a full 365 or 366-day tax year. Depending on which day of the week 6 April falls on, and whether it is a leap year, some tax years produce exactly 52 weekly pay dates for a given payday (for example, every Friday), while others produce 53, simply because of how the calendar lines up. **How HMRC handles it -- the week 53 basis** Where a genuine extra (53rd, 27th or 14th) payment falls in the tax year, HMRC allows employers to apply a special non-cumulative "week 1" style tax basis to that single extra payment, effectively giving the employee one additional week's worth of tax-free Personal Allowance for that payment, rather than treating it as if the whole year's allowance had already been used up by the preceding 52 payments. This avoids unfairly taxing the extra payment at a punitive rate purely because of a calendar quirk. **Why this can lead to underpaid tax** Because the week 53 payment effectively receives an extra slice of tax-free allowance beyond the normal 52 weeks' worth built into the employee's tax code, the employee may end up receiving slightly more tax-free pay across the year than their annual tax code strictly allows for. HMRC usually corrects this automatically in a later tax year by adjusting the employee's tax code, rather than seeking an immediate repayment, so most employees are not asked to pay a lump sum -- the correction is usually a small reduction spread through a future year's tax code. **Who is affected** This only affects employees paid weekly, fortnightly, or four-weekly (not monthly-paid employees, since 12 monthly payments always fit exactly into a tax year regardless of how the calendar falls). It is entirely a payroll administration quirk relating to the mismatch between weekly pay cycles and the fixed tax year, not something the employee needs to actively do anything about. **What to do if you notice it** If your payslip shows a "week 53" (or 27 or 14, for fortnightly/four-weekly pay) marking, this simply confirms the special tax basis has been applied correctly for that extra payment; there is no error to query, and no action is normally required from the employee. If you are ever unsure whether your tax code has been adjusted correctly to reflect a previous week 53 payment, you can check your tax code notices or Personal Tax Account online, or contact HMRC. **Worked example** A weekly-paid warehouse worker is normally paid every Friday. In a particular tax year, the calendar produces 53 Fridays between 6 April and the following 5 April rather than the usual 52. Their 53rd payment that year is taxed on the week 53 non-cumulative basis, giving them a small additional slice of tax-free allowance for that single payment rather than taxing it as if their annual allowance had already been fully used across the preceding 52 weeks.

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