Tax - Loss Carry-Back Claims | @AdamsWinter Support

Loss Carry-Back Claims

id: loss-carry-back-claims title: Loss Carry-Back Claims category: ct600-filing tags: [loss carry back, carry back, trading loss, reclaim tax, tax refund, Box 860, Box 45, prior year, offset loss, loss relief, carry-back claim, terminal loss relief, cessation, company closing, ceased trading] applies_to: [trading] difficulty: intermediate last_updated: 2026-03-19 related: [losses-brought-forward, understanding-your-tax-calculation, filing-an-amended-ct600]

If your company made a trading loss this year and paid corporation tax last year, you may be able to carry the loss back to reclaim some or all of that tax. This guide explains how loss carry-back works and your options — including terminal loss relief for companies that have ceased trading.

What Is Loss Carry-Back?

Loss carry-back allows a company to offset a current-year trading loss against profits from the previous accounting period (up to 12 months). If the previous period was profitable and tax was paid, the company can reclaim some or all of that tax.

This is different from losses carried forward, which offset future profits. Carry-back gives you a tax refund now, rather than reducing a future tax bill.

Does @AdamsWinter Support Loss Carry-Back?

@AdamsWinter does not currently support loss carry-back claims. The CT600 Box 860 (trading losses carried back) is not available in the @AdamsWinter form.

What @AdamsWinter does handle:

  • Filing your CT600 for the current loss-making year (with £0 tax due)
  • Carrying the loss forward automatically to offset future profits
  • See our losses brought forward guide for details
What you will need to do separately:

  • Submit the loss carry-back claim to HMRC (see options below)

How to Make a Loss Carry-Back Claim

You have two options:

Option 1: HMRC's Corporation Tax Online Service

  1. Log in to your HMRC business tax account
  2. File an amended CT600 for the prior year (the profitable year you're carrying back to)
  3. Include the carry-back amount in Box 860
  4. HMRC will process the refund

Option 2: Ask an Accountant

An accountant can submit the carry-back claim on your behalf, either as part of the current year's CT600 or as a standalone claim.

ℹ You can still file your current year's CT600 through @AdamsWinter showing the trading loss. The carry-back claim is a separate process that adjusts the prior year's tax position.

Key Rules

  • Time limit: Carry-back claims must be made within 2 years of the end of the loss-making period
  • Maximum period: Losses can only be carried back 12 months (one accounting period)
  • Trading losses only: Capital losses cannot be carried back against trading profits
  • Extended losses: Special rules applied during COVID (2020-2022) allowing 3-year carry-back — these have now expired for most companies

Terminal Loss Relief (Box 45) — When a Company Ceases Trading

Terminal loss relief is a special type of carry-back that applies when a company permanently ceases to trade. It is reported in CT600 Box 45.

How Terminal Loss Relief Works

When a company stops trading for good, it can carry back losses from its final 12 months of trading against profits from the 3 preceding accounting years (rather than just 1 year for a regular carry-back). This can result in a larger tax refund.

Does @AdamsWinter Support Terminal Loss Relief?

@AdamsWinter does not currently support terminal loss relief. CT600 Box 45 is not available in the @AdamsWinter form.

To claim terminal loss relief, you will need to use one of the options below.

How to Claim Terminal Loss Relief

Option 1: HMRC's Corporation Tax Online Service

  1. Log in to your HMRC business tax account
  2. File an amended CT600 for each prior year you are carrying the loss back to
  3. Include the terminal loss amount in Box 45 of each amended return
  4. HMRC will process any refunds due
Option 2: Ask an Accountant

An accountant can prepare and submit the terminal loss relief claim on your behalf. This is recommended if the amounts are significant or if you are carrying back across multiple years.

Key Rules for Terminal Loss Relief

  • The company must have permanently ceased to trade — this relief does not apply to temporary loss-making periods
  • Losses from the final 12 months of trading are eligible
  • Can be carried back against profits from the 3 years before cessation (worked on a last-in, first-out basis)
  • Claims must be made within 2 years of the end of the accounting period in which the trade ceased
  • Any losses that cannot be relieved under terminal loss relief may be carried back under the normal rules instead

Common Questions

Can I carry back a loss and carry the rest forward?

Yes. If your current-year loss is larger than the previous year's profit, you can carry back enough to eliminate the prior year's tax, and carry the remainder forward.

Do I need to file my current year CT600 first?

Not necessarily, but it helps. Filing the loss-making year's CT600 first establishes the loss amount. You can then make the carry-back claim against the prior year.

How long does the refund take?

HMRC typically processes loss carry-back refunds within 4-6 weeks of accepting the claim.

Still Have Questions?

If you need help understanding whether a carry-back or terminal loss relief claim applies to your situation, we would recommend speaking to an accountant. For questions about filing your CT600 through @AdamsWinter, get in touch.

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