HMRC Updates for September 2026: 5 Changes Small Businesses Should Know

HMRC’s latest Agent Update, published on 18th September 2026, includes several changes that affect small businesses, company directors and savers. Some need action now. Others are worth planning for over the coming months.

This guide gives you a simple summary of the five updates that matter most.

1. Directors Must Report Every Directorship on Their Tax Return

If you are a company director and you already file a Self Assessment tax return, your 2025/26 return will ask for more detail. You will need to complete a separate employment page (SA102) for each UK company directorship. This applies even if you received no salary, benefits or dividends, and even if the company was dormant.

Being a director does not, on its own, mean you must register for Self Assessment. The rules apply once you need a return for another reason, such as rental income or self-employed profits.

There are extra questions if the company is a close company. This is usually a company controlled by five or fewer shareholders, or by its directors. Most owner-managed companies fall into this group. You will need to give:

• the company’s name and registration number
• the dividends you received from it
• your highest percentage shareholding during the year

HMRC says you must answer these questions even when the figure is zero. The good news is that these rules do not change how much tax you pay. The online deadline for 2025/26 returns is 31st January 2027.

2. HMRC Is Writing to People Who Owe Tax on Savings Interest

From late September 2026, HMRC will contact people who owe tax on interest earned in 2025/26. Most people have a tax-free Personal Savings Allowance. This is £1,000 for basic rate taxpayers and £500 for higher rate taxpayers. Additional rate taxpayers get no allowance.

If you owe tax, you will receive either a P800 tax calculation or a PA302 Simple Assessment:

• Employed or on a pension through PAYE: HMRC will usually change your tax code. You do not need to do anything.
• HMRC cannot collect it through PAYE, or you owe over £3,000: you will get a Simple Assessment. If HMRC sent it before 31st October 2026, pay by 31st January 2027. If it arrives later, pay within 3 months of the letter date.
• Savings income over £10,000: you must file a Self Assessment return.

Some people may get a second notice for the same year. This shows the total for the whole year, so take off anything you have already paid. If you think a Simple Assessment is wrong, contact HMRC within 60 days.

3. Certificate of Residence Applications Have Moved Online

A certificate of residence proves to a foreign tax authority that you are UK resident for tax. It helps you claim relief so you are not taxed twice on income from abroad. A letter of confirmation does a similar job where there is no double taxation agreement.

HMRC now asks everyone to use one online application form. This now includes companies, partnerships and public bodies. You can upload overseas tax forms, save your progress and get a reference number to track your application.

4. Class 1A National Insurance for Voluntarily Payrolled Benefits

From 6th April 2027, employers must report company cars, fuel, vans and private medical benefits through payroll. You can choose to payroll other benefits too, such as employment-related loans and accommodation.

HMRC has confirmed that if you do this, you must also pay the Class 1A National Insurance through payroll. You cannot report it separately at the end of the year.

Key dates to note:

• November 2026: registration opens for voluntary payrolling in 2027/28
• Already registered? You will carry on automatically
• 5th April 2027: the deadline to withdraw

Note: In July 2027, you will pay Class 1A on 2026/27 benefits under the old P11D system while also paying in real time. Plan your cash flow for this now.

5. A New Tool to Check Your Tax Deadlines

HMRC has launched a free tax deadline checker. It covers Self Assessment, VAT, PAYE for employers and CIS for contractors. HMRC plans to add more taxes later.

You do not need to sign in, and HMRC confirms your answers are not sent to it. It takes around 5 minutes. You can then print your dates or add them to your calendar.

For the most current information, always check the official GOV.UK Agent Update issue 147.

When Getting Advice Can Help

Keeping up with HMRC changes is hard when you are busy running a business. You are not expected to be an expert, and getting professional advice can be very helpful.

If you would like calm, practical support, Penney’s Accountancy works with UK small businesses in and around Farnborough and the surrounding areas. We can help you understand which of these updates affect you, complete your tax return correctly and plan ahead for April 2027.

Want to Learn More in Your Own Time?

For those who want to build their confidence and understand these topics in more detail, Penney’s Finance School offers an online, self-paced business and finance course. It covers everything from company setup to cash flow and tax, allowing you to learn at your own pace.

Important information

The information provided in this article is intended as general guidance for UK businesses only and reflects UK tax legislation and HMRC guidance as of September 2026.

Tax rules and business requirements can change, and individual circumstances vary. Before acting on any of the information above, we recommend speaking to a qualified accountant who can provide advice tailored to your specific situation.