# Loss Carry-Back Calculator

> Work out the Corporation Tax repayment from carrying a company's trading loss back to the previous year, and compare it with carrying the loss forward.

Enter this year's trading loss and last year's profit to see the repayment from carrying the loss back, and how that compares with carrying it forward.

Use the calculator: https://www.taxoptimiser.co.uk/calculators/loss-carry-back

Example: A trading loss of £30,000 in the year to 31 March 2026, carried back against a profit of £80,000 the year before, brings a Corporation Tax repayment of £7,950.00.

## Carrying a loss back

A company can set a trading loss against its total profits of the previous 12 months and have the Corporation Tax on those profits repaid. The claim is made in the Company Tax Return for the loss-making period, within two years of the end of that period.

## Carrying a loss forward

Any loss not carried back is carried forward and set against future profits. Carrying back brings a repayment now at last year's rate; carrying forward may save more if next year's profits will be taxed at a higher rate.

## When the trade has stopped

A loss made in the final 12 months of a trade can be carried back against the profits of the previous three years, most recent first.

## Frequently asked questions

### How far back can a company carry a trading loss?

12 months. A loss made in the final 12 months of a trade can be carried back three years, most recent first.

### How do I claim loss carry-back?

In the Company Tax Return for the loss-making period, within two years of the end of that period.

### Is it better to carry a loss back or forward?

Carrying back brings a repayment now at last year's rate. Carrying forward may save more if next year's profits will be taxed at a higher rate. The calculator shows both.

## Related calculators

- [Corporation Tax Calculator](https://www.taxoptimiser.co.uk/calculators/corporation-tax.md): Estimate Corporation Tax for a UK limited company with marginal relief.
- [Capital Allowances Calculator](https://www.taxoptimiser.co.uk/calculators/capital-allowances.md): Full expensing, AIA and car allowances on what your company has bought.
- [Corporation Tax Deadlines Calculator](https://www.taxoptimiser.co.uk/calculators/corporation-tax-deadlines.md): Payment, CT600 and Companies House dates for any accounting period.

## Sources

- [Corporation Tax: calculating and claiming a loss](https://www.gov.uk/guidance/corporation-tax-calculating-and-claiming-a-loss) (GOV.UK)
- [Corporation Tax rates and allowances](https://www.gov.uk/corporation-tax-rates) (GOV.UK)

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Last updated 11 October 2026. Guidance only: a general estimate, not tax advice. Published by Tax Optimiser, UK tax filing software (https://www.taxoptimiser.co.uk).