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CT600 box 285: claiming trading losses against total profits

Last updated: 16 October 2026

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. In the filing wizard: Trading losses to claim against total profits (box 285) sets how much of your eligible brought-forward trading losses reduces this return’s total profits: leave it blank for the maximum shown, or enter 0 to claim nothing.

Go to the steps and entry details

On this page

Boxes 160 and 285Blank means maximumEach return of a long periodWhere you see it: Financial Data › Tax adjustments › Trading losses brought forward

Before entering figures, the filing setup questions can set the existing destination and CT600 route for an ordinary limited company. They keep the full accounts dates beside the CT600 dates. You can also continue with the controls below without opening the questions.

What these fields do

Trading losses to claim against total profits (box 285) sets how much of your eligible brought-forward trading losses reduces this return’s total profits: leave it blank for the maximum shown, or enter 0 to claim nothing.

  • Enter your whole unused pool in Trading losses brought forward. The claim field and the same-trade-only field appear once the pool is above 0.
  • The same-trade-only part, entered in Losses from before 1 April 2017, or from a trade carried on wholly outside the UK, reduces trading profit automatically in box 160. It is not part of the box 285 claim.
  • Blank and 0 are different. Blank claims the maximum shown. 0 makes no box 285 claim, and the eligible losses all carry forward. See the difference
  • Whatever is not used carries forward while the trade continues, and the review page shows it.
  • A period longer than 12 months has a claim and an allowance for each CT600. Two accounting periods

For a loss from a trade carried on wholly outside the UK, use the CT600 box 790 guide. The loss cannot reduce other profits under section 37 or be carried back. While the trade continues, it carries forward against the same trade. On a two-return filing, one location answer applies to both returns.

Is this the right guide for you?

Use it if all of these are true

  • Your prepared tax computation shows unused trading losses from earlier periods.
  • The company still carries on the same trade.
  • Under What the company does you chose Trading or Both.

Do not use it if

Common mistake: entering 0 when you meant the maximum

The claim field starts blank and shows the maximum as a placeholder. Blank claims that maximum. Typing 0 tells HMRC you make no box 285 claim this period. Aspen Example Ltd has £30,000 of eligible losses, £20,000 of trading profit and £2,000 of bank interest:

0 entered: no box 285 claim

Taxable total profits
£22,000
Losses carried forward
£30,000
Corporation tax due
£4,180

Left blank: the maximum is claimed

Taxable total profits
£0
Losses carried forward
£8,000
Corporation tax due
£0

A claim of 0 or of a smaller amount can be a deliberate choice. How much to claim is for you or your accountant to decide. If the claim field shows an error, a Use maximum button beside it puts it back to blank.

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.

The difference shows in the tax. If Aspen Example Ltd's whole £30,000 were same-trade only, it could reduce only the £20,000 of trading profit. The £2,000 of interest stays taxable:

Whole pool eligible for box 285
Taxable total profits £0, tax £0, £8,000 carried forward
Whole pool same-trade only (box 160)
Taxable total profits £2,000, tax £380, £10,000 carried forward

The company and all figures on this page are fictional.

More help: HMRC Company Tax Return guide: box 285 · Box 160

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.

Worked example

Company
Aspen Example Ltd
Accounts period
1 April 2025 to 31 March 2026 (12 months)
Figures
Turnover £60,000, staff costs £25,000, other charges £15,000, bank interest £2,000
Unused trading losses
£30,000, all arising after 1 April 2017 and eligible for box 285, from the company’s prepared computation

The company and all figures on this page are fictional.

4. Enter your claim

SimpleCompanyTax files the box 285 claim using the figures you supply.

  1. Company Profile & Period

    Accounting period
    1 April 2025 to 31 March 2026
    Trading status
    ActiveThe form starts on Dormant, so make sure you change it.
    What the company does
    TradingThe trading loss fields are not shown for Property only.

    Click Next →.

  2. Financial Data

    Previous year
    Last year’s figures, from your previous accountsRequired before you continue. Figures from Companies House fill in where available. Check them, and enter 0 where a line had no amount.
    Turnover
    60000
    Cost of raw materials and consumables
    0Required. Enter 0 when there are none.
    Staff costs
    25000
    Other charges
    15000
    Balance sheet
    Your balance sheet at the end of the period
    Average number of employees
    Your average number, or 0
    Interest receivable and similar income
    2000
    Trading losses brought forward
    30000Under Tax adjustments. Enter the full unused pool, including any same-trade-only part, even in a loss year.
    Losses from before 1 April 2017, or from a trade carried on wholly outside the UK
    Leave blankEnter the same-trade-only part here: losses from before 1 April 2017, the pre-April part of a straddling period and later losses restricted under section 45B. Blank or 0 means none.
    Trading losses to claim against total profits (box 285)
    Leave blankBlank uses the maximum shown. Enter a smaller whole-pound amount, or 0 to make no box 285 claim. This does not restrict the automatic same-trade relief.
    Company deductions allowance
    Leave blankBlank uses the displayed maximum. Enter the allowance available to this company for that return if it is lower.

    Click Next →.

    More help: Where to find your loss figure

  3. Review & file

    The Corporation tax due card for Aspen Example Ltd:

    Corporation tax due
    £0 .00
    On taxable total profits of £0 at 19.0% · small profits · limits applied £50,000 to £250,000
    Trading losses carried forward
    £8,000The unused balance after this return.
    Preview your documents (free)
    Check boxes 160 and 285 and the computationThe computation shows the claim, the tax and the losses carried forward.

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. Use the loss carry-back guide to claim from a loss-period return. 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.

Each claim row identifies its return when both returns are shown together. Beech Example Ltd has the same figures and losses over the 18 months 1 January 2025 to 30 June 2026, with both claims left blank:

CT600 1: 1 January 2025 to 31 December 2025
Tax £0, £15,293 left for the second return
CT600 2: 1 January 2026 to 30 June 2026
Tax £0, £8,000 carried forward from the whole period

The company and all figures on this page are fictional.

More help: How the dates are split · Reading the losses in each computation

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%.

The review card reads the same way. For Aspen Example Ltd, the line is "On taxable total profits of £0 at 19.0% · small profits · limits applied £50,000 to £250,000", with £0 due.

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

£0Tax with the maximum claimed, £8,000 carried forward
£4,180Tax with 0 entered, £30,000 carried forwardBlank or 0
Box 285The total-profits claim. Same-trade relief goes in box 160.

Related guides

Open the guide that matches your losses.

Using trading losses to reduce your Corporation TaxWhere the figure comes from and what carries forward.Property income and lossesLosses from letting property.Why does my Corporation Tax show 25%?Read the rate and band on the review page.

Looking for a different field or step? See all filing wizard guides →

Official sources

Whether this route matches your filings is for you to decide, yourself or with your accountant.

Example companies and figures are fictional. Field names match the filing wizard as of 12 October 2026.