CT600 box 285: claiming trading losses against total profits

Short version. Eligible trading losses arising from 1 April 2017 can be carried forward and claimed against total profits under section 45A. The claim goes in CT600 box 285 and can reduce trading profit, interest, property profits and box 205 income. Older losses and some later losses are restricted to the same trade and use box 160.

1. Which losses qualify

Use the unused eligible amounts in your prepared tax computation, after earlier relief and any group surrender. The company must continue the trade. Commercial-basis rules apply, and a trade becoming small or negligible can restrict later use of its losses. There are specific rules for ring-fence trades and insurance companies. Read the full HMRC conditions for the first carry-forward and the conditions in subsequent periods.

A loss moved to same-trade-only treatment under section 45B cannot later return to section 45A. For a period straddling 1 April 2017, the before-April and from-April portions need separate treatment. Do not classify the whole loss from the period start date. See HMRC’s transitional rules.

2. Box 160 or box 285

Box 160 reports same-trade relief. Box 285 reports the eligible total-profits claim, including the part used against trading profit. A post-reform claim can therefore move from box 160 to box 285 when you update an older draft, even when the tax stays the same. A loss entered as an opening balance is not necessarily the amount used this year.

3. Choose the amount to claim

You can claim all or part of an eligible pool. For example, £5,000 of eligible losses and £800 of profits remaining after current-year relief allow a claim of £800, leaving £4,200 carried forward. A £300 claim leaves £500 of profits and £4,700 carried forward. A zero claim leaves the full pool available for later periods, subject to the rules.

A claim is normally due within two years of the end of the period in which relief is claimed, or a longer period allowed by HMRC. The carried-forward loss restriction can limit relief. This service supports claims where the company deductions allowance covers qualifying profits, and does not calculate the wider restriction. See HMRC’s claim guidance.

4. Enter your claim

SimpleCompanyTax#Simple CompanyTax files the box 285 claim using the figures you supply.

1. Open Financial data, then Tax adjustments. Enter the full unused pool in Trading losses brought forward.
2. In Losses brought forward from before 1 April 2017, enter the same-trade-only part. Include the pre-April part of a straddling period and any later losses restricted under section 45B. Leave blank or enter 0 if none of the opening pool is restricted.
3. Check the maximum shown for Trading losses to claim against total profits (box 285). Leave blank to use it, enter a smaller whole-pound amount, or enter 0 to claim nothing.
4. Review the Company deductions allowance. Leave blank for the displayed maximum or enter the allowance available to this company for that return.
5. Continue to Review and check the claim, tax and carried-forward losses. Existing saved drafts keep their earlier calculation until you reopen and save the filing details.

Same-trade-only relief is automatic in this service. The box 285 claim field does not restrict box 160 relief. Carry-back claims, group relief and elections to restrict automatic same-trade relief need another filing method.

5. Two accounting periods

A period longer than 12 months has a separate claim and deductions allowance for each CT600. The second return starts with losses left after the first, including an unrelieved loss arising in it. Check both maxima and both claims. The closing computation reports the final remaining pool, not the sum of both returns’ closing balances.

6. Why does 19% still appear beside £0 tax?

The percentage beside Corporation tax identifies the calculation’s rate band. It is not an additional charge. Read the pound amount on that row and the amount under Corporation Tax due on Review & file.

If both show £0, the amounts agree. A £400 loss before tax remains a £400 loss after a £0 tax charge, even when the rate label still says 19.0%.

These controls record your prepared figures and treatment. They do not establish legal eligibility. This is general filing guidance, not accounting or tax advice.