P800 Tax Checker, 2026/27

How this is calculated

This checker calculates the income tax that should be due on your total employment and dividend income for 2026/27, using the £12,570 personal allowance (tapered above £100,000), the 20% basic rate band up to £37,700 of taxable income, the 40% higher rate band up to £125,140, and 45% above that, together with the £500 dividend allowance and the dividend rates.

It then compares that figure to the tax actually deducted from your pay through PAYE across the year. A shortfall suggests HMRC may issue a P800 asking for more tax; a surplus suggests a refund is likely, subject to the fuller checks HMRC runs.

This is a simplified version of the real P800 process: HMRC's calculation also reconciles month-by-month tax code changes, benefits in kind reported on a P11D, and any other income HMRC already knows about.

Why P800s happen

A mismatch commonly arises from a mid-year tax code change, starting or leaving a job partway through the year, having more than one PAYE source at once, or a benefit in kind being coded incorrectly.

Directors who also draw dividends often see a P800-style shortfall because PAYE only ever collects tax on salary, never on dividends, so the dividend tax has to be settled separately through self-assessment rather than through a P800 at all.

What to do next

If HMRC sends a genuine P800 showing a refund, it is usually paid automatically or claimable online. If it shows an underpayment, HMRC typically collects it by adjusting next year's tax code rather than demanding a lump sum, unless the amount is large.

If you already complete a self-assessment return, HMRC does not normally issue a P800 at all, since the annual return itself performs this reconciliation.

What is a P800?

A P800 is a tax calculation letter HMRC sends when the tax collected through PAYE across a year does not match what you actually owed, showing either a refund or an amount still due.

Will I get a P800 automatically if I am owed a refund?

HMRC's own systems normally trigger a P800 automatically once their end-of-year reconciliation runs, usually between June and October after the tax year ends, but it is worth checking rather than waiting if you suspect an overpayment.

Does a P800 cover dividend income?

No. P800s only reconcile PAYE income such as salary, pensions and taxed benefits. Dividend tax and other untaxed income are dealt with through self-assessment instead.

What if I disagree with a P800 figure?

You can query it with HMRC and provide evidence such as final payslips or P45s. Errors often arise from an employer reporting benefits late or a tax code not updating in time.