The Bill Without a Return: HMRC Simple Assessments in 2026/27

Most UK tax bills begin with a return. A taxpayer gathers the paperwork, files by the deadline and pays what is due. A Simple Assessment turns that sequence on its head. HMRC can issue a formal calculation without asking for a return, and the result still carries legal weight. In 2026/27, with Simple Assessments for the 2025/26 tax year capable of landing on doormats before the 31 January 2027 payment date, it is worth understanding what the document is and what to do with it.

What a Simple Assessment actually is

A Simple Assessment is a formal HMRC calculation of tax that the department believes is owed. It is usually issued on form PA302. It is not a polite enquiry, a preliminary estimate or a reminder to file. It is a demand for payment, and HMRC expects it to be settled by the date shown on the letter.

It is often confused with a P800 tax calculation. A P800 is an informal calculation that frequently leads to a change in a PAYE tax code, so that the tax is collected through wages or pensions. A Simple Assessment is different. It is used where the tax cannot conveniently be collected through PAYE, and the taxpayer is expected to pay HMRC directly.

The letter should set out the tax year, the income HMRC has used, the allowances and reliefs applied, the tax already treated as paid and the final amount due. It may also include a reference number and payment instructions. The figures are based on information HMRC holds, often from the Department for Work and Pensions, employers, pension providers or banks. That information can be accurate, but it can also be incomplete or applied in the wrong way.

Why HMRC may send one instead of asking for a return

A Simple Assessment is generally used where HMRC does not think a full Self Assessment return is necessary, but there is still tax to collect. A common example is a pensioner whose state pension and private pension together exceed the personal allowance, with the excess tax not collectable through the PAYE code. Savings interest, small amounts of untaxed income and certain other adjustments can also lead to a Simple Assessment.

The practical point is that not receiving a Self Assessment return does not mean no tax is due. If HMRC has enough information to calculate a liability, it can issue a Simple Assessment instead. Ignoring the letter because no return was requested is a mistake. Late payment interest can accrue, and HMRC can pursue the amount through its usual collection powers.

What to check before paying

Before making a payment, read the letter carefully and compare it with your own records. Check the tax year, your name and address, the income sources listed and the tax already treated as paid. A simple mismatch, such as an old pension figure or an omitted relief, can change the amount significantly.

Gather the documents that support your position: P60s, pension statements, bank or building society interest certificates, Gift Aid records and any coding notices. If the letter says tax is due because an item was untaxed, confirm whether that is correct. If it says tax has not been collected through PAYE, check your tax code and payslips for that year. It is also worth checking whether you had already filed a Self Assessment return for the same year. If you had, the Simple Assessment may be duplicate or based on outdated information.

If the calculation is correct, pay by the deadline shown. For a Simple Assessment covering the 2025/26 tax year, the date is commonly 31 January 2027, but the letter itself is the authoritative source. If the deadline has already passed, pay as soon as possible and consider contacting HMRC about interest or a payment arrangement.

If the figure looks wrong

Do not simply pay a figure you believe is incorrect, and do not ignore it. Contact HMRC using the details on the letter, normally within 60 days of the date of the assessment. Explain clearly which figure is wrong and why, and provide evidence where possible. Ask for a breakdown of the calculation if the letter does not provide enough detail.

If the dispute relates to estimated income, provide the actual figures. If you believe a relief or allowance has been missed, say so and supply the supporting documents. If you think you should not have received a Simple Assessment at all, explain why, for example because you already file a Self Assessment return or because the tax has been collected another way.

Ask HMRC whether collection of the disputed amount will be paused while the matter is reviewed. Do not assume that contacting HMRC automatically stops interest or collection. Keep a copy of the letter, your correspondence and any evidence you send. A dated record is useful if the matter takes time to resolve.

If you have already paid the tax another way

Sometimes a Simple Assessment arrives after the tax has already been settled. This can happen where a PAYE code was adjusted, a Self Assessment return was filed, or a payment was made under a different reference. In that situation, contact HMRC and explain how and when the tax was paid. Provide evidence such as payslips, a P60, a coding notice, a Self Assessment statement or bank records showing the payment.

If the tax was collected through PAYE, HMRC may need to amend its records rather than issue a refund. If it was paid directly, ask for the payment to be traced and allocated correctly. If a duplicate payment has been made, ask how it will be refunded or set against another liability. Keep the correspondence until the position is confirmed in writing.

A practical sequence

Open the letter and note the tax year, the amount, the payment deadline and the reference. Compare the figures with your records. If the calculation is right, pay on time. If it is wrong, contact HMRC within the period stated on the letter, explain the error and supply evidence. If you cannot pay in full, contact HMRC before the deadline to discuss a payment arrangement. Keep copies of everything.

A Simple Assessment is not a scam simply because it arrives without a return. It is a formal bill that deserves a formal response. Checking it carefully, paying what is genuinely due and challenging what is not is the practical way to deal with it in 2026/27.