Tax overpayments and underpayments

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If your tax calculation letter (P800) says you owe tax

HM Revenue and Customs (HMRC) will collect the tax you owe over the next year. This will happen automatically if you:

  • pay Income Tax through an employer or pension provider
  • earn enough income over your Personal Allowance to cover the underpayment
  • owe less than £3,000

HMRC will write to you about how you can pay if they cannot collect the money this way.