Households who earned more than £10,000 from savings and investments outside an ISA in the past financial year are required to file a self-assessment tax return, according to tax experts at investment and savings platform AJ Bell. Failing to file and pay on time could result in a fine and an interest rate of 7.75% on any unpaid money.
Deadlines and who needs to file
His Majesty’s Revenue and Customs (HMRC) urges liable households to file a self-assessment tax return every year. While many workers who only earn a regular wage via PAYE will not need to do so, many others must file a return before October 31 if using paper returns, or before January 31.
According to financial experts at AJ Bell, those who earned more than £10,000 in savings and investments outside of an ISA in the past financial year also need to file a return. Other circumstances requiring self-assessment include repaying some Child Benefit or earning money on the side, such as from selling online.
When you must file a return
You must file a tax return for 2025-26 if any of the following applied during that tax year:
- You worked for yourself and earned more than £1,000
- You had to pay capital gains tax on something you sold or transferred for a profit
- You had to pay the High Income Child Benefit Charge and do not pay it through PAYE
- You were a partner in a business partnership
“Even if none of the above apply to you, you might still have to file if you’ve received more than £10,000 from savings and investments in the tax year.”
Changes to the £150,000 rule
Charlene Young, from finance firm AJ Bell, previously revealed that a £150,000 rule for high earners is no longer in place, but those whose circumstances have changed may still need to file as well. She added: “In previous years, taxpayers had to file if they earned over a certain threshold (£150,000 last year). Although that rule has now fallen away where a person’s only income source is taxed under PAYE, many people wrongly believe they don’t need to file if their circumstances simply change or they have no tax to pay. This is only true if you’ve told HMRC about your change in circumstances, or they’ve already confirmed to you directly that you don’t need to file.”
“If HMRC wrote to you asking you to send a return but you believe you don’t need to, you’ll need to tell them as soon as possible. HMRC might not be aware of changes in your circumstances, so if you don’t let them know, you still risk a fine for not filing, even if you have no tax to pay.”
“If you’re at all unsure, you can check whether you need to complete a tax return using this handy tool on the government website. And even if you don’t have to file, you might still need to tell HMRC directly about a side hustle or any other ways you top up your income.”
Payment deadlines and interest
Those who are liable to file and pay tax need to do so by midnight on January 31, 2027, for the tax year April 6 2025 to April 5 2026, or they face a 7.75% interest rate on any unpaid money and a fine on top.
Young added: “And finally, don’t forget to pay on time too. Whenever you filed (or plan to), make sure you’ve paid what you owe by midnight on 31 January 2026. If you don’t, you’ll start to accrue daily interest from 1 February. The annual interest rate charged by HMRC will sit at a whopping 7.75%... with further surcharges if the bill remains unpaid months later.”
“If you’re having difficulty paying, you might be able to agree a payment plan online with HMRC as long as you owe £30,000 or less. You can also apply to reduce your payments on account for the next year if you think your earnings will be significantly lower than before.”
