Not every year in business is a profitable one. HMRC recognises this, and allows self-employed people, partners, and landlords to use losses to reduce tax — sometimes on other income altogether, not just on the business that made the loss.
The rules are generous but strict about timing and records. Choose the wrong relief and you either overpay or miss out.
The main types of loss relief
Sideways loss relief
If you are self-employed and make a trading loss, you can usually set it against your other income (such as employment or rental income) for the same tax year or the previous one. This is called sideways relief. For some businesses the amount that can be offset is capped at the greater of £50,000 or 25 per cent of your total income.
Carry forward relief
If you cannot use a loss now, you can carry it forward against future profits from the same trade indefinitely. There is no time limit, but the losses can only be used against the same business that made them.
Opening and closing years
In the early years of a business, losses in any of the first four years can be carried back three years against other income. At the end of a business, terminal loss relief allows you to carry losses in the final 12 months back three years against profits from the same trade.
Property losses
Property losses cannot be offset against other income. They are ring-fenced to property profits and must be carried forward to use against future rental profits only. This is one of the biggest differences between trading and letting income.
How to claim
Claim loss relief through your Self Assessment tax return. The right boxes depend on which relief you are claiming, but the time limit is usually four years from the end of the tax year of the loss. Miss it and the relief is lost.
Use our self-employed tax calculator to see how a loss year affects your tax position, and whether sideways or carry-forward relief produces the better result.
Worked example
Say you earn £50,000 from employment and £10,000 of loss from a sole trader business in the same year. Sideways relief could reduce your taxable income to £40,000, saving around £4,000 in tax.
Alternatively, carrying the loss forward to use against £15,000 of sole trader profit next year would save a smaller amount because you are comparing the loss against a much smaller base. For most people, using the loss now is more valuable than using it later.
Traps to watch
- Hobby businesses are not allowed to claim sideways loss relief. HMRC can refuse the claim if there is no realistic profit motive.
- Losses must be genuine; you cannot create a loss just to offset other income.
- Sideways relief uses up your personal allowance first, so claiming a very small loss can waste the allowance.
- Partners in a partnership have similar rules, but partnership losses have their own limits.
The bottom line
Loss relief is often worth more than people think, but the rules reward tidy records and prompt claims. If you have had a weak trading year, run the options through a calculator (or an accountant) before the filing deadline so you pick the relief that saves the most tax.