How do I appeal or query a P800 tax calculation from HMRC?

Full answer

A P800 tax calculation is a letter HMRC sends automatically, generally between June and November following the end of a tax year, to employees and pensioners whose PAYE tax deductions throughout the year did not exactly match their actual final tax liability — this can happen for many reasons, including a change of job partway through the year leading to gaps or overlaps in tax code application, an emergency tax code being used temporarily, multiple sources of PAYE income not being coordinated correctly across employers, or a benefit-in-kind or other adjustment not being reflected in your tax code during the year itself. If the P800 shows you are owed a refund, HMRC usually pays this automatically (either directly into a bank account if you claim it online promptly, or by cheque after 45 days if unclaimed) — but if it shows you owe additional tax, this is usually collected by adjusting your tax code for the following tax year, spread across your future paycheques, rather than requiring an immediate lump sum payment, unless the balance is unusually large or you have no ongoing PAYE income to collect it through. If you believe the P800 calculation itself is wrong — for example, it appears to be missing income you know was correctly taxed, applies an incorrect tax code, does not reflect Marriage Allowance or another relief you are entitled to, or double-counts a benefit-in-kind already taxed through your payslip — you should contact HMRC promptly by phone, via the online HMRC personal tax account webchat, or in writing, clearly explaining what you believe is incorrect and providing supporting evidence such as final payslips, your P60, or P11D benefit-in-kind statements from your employer. HMRC will review the calculation against the evidence provided and issue a revised P800 if your query is upheld, or explain why the original figure is considered correct if not. Because P800s are calculated automatically from the PAYE information HMRC holds, querying promptly when something looks wrong (rather than assuming HMRC's system is always correct) is worthwhile, particularly if you have complex circumstances such as multiple jobs, benefits in kind, or a mid-year change of employer during the relevant tax year. Use the Take-Home Pay and Tax Code Checker calculators to sense-check your own expected annual tax position.

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