Most people assume HMRC will tell them if they need to complete a tax return. In reality, the responsibility usually falls on the taxpayer to recognise when additional income or gains need to be reported.
With the wide range of income sources, allowances and reporting thresholds now in place, it is not always straightforward to establish whether a Self-Assessment tax return is required. In some cases, a full tax return may not be necessary, but HMRC may still expect you to report additional income separately.
To help clarify these requirements, Alun Evans, a Partner at our Haverfordwest office, outlines common situations where individuals must register for Self-Assessment and report extra income to HMRC.
What is Self-Assessment?
Self-Assessment is the system HM Revenue & Customs (HMRC) uses to collect Income Tax and Capital Gains Tax, where tax has not already been deducted automatically.
For employees, tax is normally collected through the PAYE system. However, if you receive other income or need to report gains or claim certain tax reliefs, you may also need to complete a tax return.
Common Reasons You May Need to Submit a Tax Return
Self-employment and partnership income
You will usually need to register for Self-Assessment if you are self-employed and your total trading income exceeds £1,000 in a tax year before expenses are deducted.
If your income is below this level, it may be covered by the trading allowance, and no tax return may be required.
If you are a partner in a business partnership, you will normally need to complete a tax return regardless of the level of income received.
Rental income
Many landlords are unaware that rental income can trigger a requirement to complete a tax return.
If you receive income from letting property, you may need to report it to HMRC, particularly if rental profits exceed the available allowances. We regularly assist landlords who have unintentionally fallen behind with their tax reporting obligations, sometimes over several years.
Investment and overseas income
You may also need to complete a tax return if you receive:
- untaxed income of more than £2,500;
- significant dividend or savings income;
- foreign income;
- income from a trust; or
- income that has not been fully taxed at source.
In some cases, even where no additional tax is due, HMRC may still require the income to be declared.
Capital gains
A tax return may also be required if you dispose of assets such as property, shares or investments and make a taxable capital gain.
It is important to remember that gains arising on the sale of a residential property that has been let out must generally be reported to HMRC and any Capital Gains Tax paid within 60 days of completion.
Claiming tax reliefs
Self-assessment is also used by many taxpayers to claim additional tax reliefs, including:
- higher-rate tax relief on personal pension contributions; and
- additional relief on charitable donations made under Gift Aid.
Other circumstances
Other situations where a tax return may be required include:
- where you need to repay a student or postgraduate loan outside the PAYE system;
- where you claim more than £2,500 in employment expenses; or
- where you are a non-UK resident but receive taxable UK income.
What Changed in April 2026?
From April 2026, many higher earners and individuals subject to the High Income Child Benefit Charge no longer need to submit a Self-Assessment tax return solely for that reason, as the charge can now be collected through PAYE.
However, if you have already completed a tax return for other reasons, details of any Child Benefit received during the tax year will still need to be included.
Situations Where You May Still Need to Contact HMRC
There are also circumstances where a full Self-Assessment tax return may not be required, but HMRC still expects additional income to be reported separately.
Examples can include:
- employment expenses below £2,500;
- smaller amounts of untaxed income;
- modest levels of rental income;
- savings or dividend income below reporting thresholds; and
- small amounts of self-employed income.
The reporting requirements in these areas can be complex and are not always intuitive, particularly where multiple sources of income are involved.
How We Can Help
Understanding when you need to submit a tax return is not always straightforward, and the rules continue to evolve.
At Bevan Buckland, we help clients review their reporting obligations and ensure they submit the correct information to HMRC on time.
If you are unsure whether you need to complete a Self-Assessment tax return, or would like advice on your wider tax position, please get in touch by emailing mail@bevanbuckland.co.uk or by contacting your usual Bevan Buckland adviser.
