UK workers receiving an extra paycheque on April 4th or 5th face unexpected tax bills due to a little-known rule.

Thousands of UK workers face unexpected tax bills due to a little-known rule, warns the Low Incomes Tax Reform Group (LITRG). Those paid weekly, fortnightly, or four-weekly who receive an "extra" paycheque on April 4th or 5th may owe additional tax in the 2023/24 tax year. If paid weekly, workers receive 53 paydays instead of 52, causing HMRC to allow employers to give more tax-free personal allowance than usual, resulting in underpaid tax.