What is a Simple Assessment tax bill and how to pay online

Simple Assessment is designed to make tax filing easier, yet many people still find the process confusing. It focuses on straightforward income reporting, basic allowable expenses, and quick online submission, which is ideal for individuals with uncomplicated finances.

Simple Assessment makes tax filing easier by focusing on basic income, simple expenses, and quick online submission. It’s ideal for those with uncomplicated finances who want a faster, stress-free way to stay compliant.

In this blog, we’ll explain how Simple Assessment works, who qualifies, and what information you need to get started.

What is a Simple Assessment tax bill?

When it comes to paying income tax, under HM Revenue and Customs (HMRC) rules, individuals can pay income tax in three main ways:

• Under the Pay as You Earn (PAYE) system.
• By submitting a Self Assessment tax return.
• By receiving a Simple Assessment calculation.

You may receive a Simple Assessment letter from HMRC if:

• HMRC finds, during their annual PAYE reconciliation process, that you have underpaid tax.
• Income Tax can’t be collected through adjustments to your PAYE code.
• You no longer need to complete a Self Assessment tax return, but you still have a tax bill to pay.

A Simple Assessment applies to any person who owes income tax but does not fall under HMRC’s self assessment criteria and/or does not have a source of PAYE.

In effect, a Simple Assessment is HMRC’s method for collecting tax owed from people who should be paying income tax but aren’t, and it usually applies to those with straightforward financial affairs.

Who has to pay under Simple Assessment?

In accordance with standard HMRC practice, if a person should be paying income tax, they are required to notify HMRC within six months of the end of the tax year. The tax year ends on 5 April; therefore, HMRC should be notified by 5 October.

HMRC does not require a notification if:

• You are already registered for self-assessment.
• All of your income is taxed under PAYE or deducted at source, at the correct rate of tax. (link to tax rates on their site).
• You have received a simple assessment which states the income tax due.

Receiving a Simple Assessment bill

Usually HMRC send a Simple Assessment letter to you by post. It can also be sent directly to your online personal tax account if you have this set up.

The letter will include:

• Your taxable income.
• Any tax you have already paid.
• Outstanding tax owed.

How to pay your Simple Assessment

The tax due, as stated in the Simple Assessment Letter from HMRC, can be paid in the following ways:

• Through your online HMRC account, if you have set one up.
• By bank transfer.
• By cheque.
• Through the HMRC app.

What is the time frame for paying a simple assessment?

Your payment deadline depends on when you received the assessment letter from HMRC.

• If you receive the letter before 31 October, your payment deadline is 31 January.
• If you receive the letter after 31 October, your payment deadline is within 3 months of the letter’s date.

Checking your Simple Assessment calculation

Simple Assessments are based on the information that HMRC has in relation to your tax payments. Sources of information include, but aren’t limited to, state pension and bank interest.

Mistakes can be made by HMRC, so it’s essential that you check the figures in the assessment.

Documents that are helpful when reviewing the Simple Assessment figures, include:

• Bank statements.
• P45 or P60.
• Pension benefit summary.
• Savings interest.
• Other income or benefits received.

What to do if you think HMRC have made a mistake

If the information and figures in your Simple Assessment don’t look right, take action quickly. You have a maximum of 60 days from the date of the letter to query the details with HMRC. You can write to HMRC or call them on the phone.

Make sure you have details of which figures you disagree with, what you think the figures should be and that you are able to provide supporting evidence if HMRC ask for it.

What happens once you’ve lodged a query with HMRC?

If HMRC agree that they have made an error, they will issue a revised Simple Assessment. If they disagree, they will send you a letter explaining their reasoning.

You have the right to appeal, but you must do so within 30 days of receiving the decision letter from HMRC.

Even if you are lodging a query, you must still pay your tax on time. If HMRC revise their assessment, they will issue you with a refund.

Avoiding late payment penalties

If you fail to pay tax by the due date, HMRC can charge you interest. According to HMRC, from August 2025, the rate of interest charged on most taxes is 8%.

If under Simple Assessment, you owe tax of between £32 and £50,000 and you don’t already have a payment plan or debt with HMRC, you are now able to apply online for a time to pay arrangement with HMRC. This allows you to pay the tax you owe in instalments.

If you enter into a time to pay arrangement, note that HMRC will still charge interest on the overdue tax, calculated from the date the original tax payment was due.

A Simple Assessment isn’t cause for an alarm. Make sure you deal with the letter and make any tax payments due.

Why work with dns accountants?

At dns accountants, we focus on helping families and business owners grow, manage, and safeguard their wealth. Our team of tax specialists has extensive experience of tax compliance and supporting clients with their personal tax accounts.

Contact dns on 03300 886 686 or email us at [email protected].

About the author

Siddharth Agarwal
I am a Chartered Tax Advisor (OMB) and ACCA. I have 9+ years of experience in owner-managed business taxation issues, company reorganisations, property taxation, and succession planning. I also work with private clients on bespoke tax planning strategies for trusts, residence status, and non-residents. I aim to fulfil my professional duties towards my clients and keep them satisfied, my utmost priority. I believe in establishing and maintaining businesses and personal relationships as the key to mutual growth.