Loss Carry-Back Calculator

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.

The loss

Loss period start

Loss period end

Trading loss for the period (£)

GBP

The trade stopped in this period A loss in the final 12 months can go back three years.

Taxable profit, previous year (£)

GBP

Expected profit next year (£, optional)

GBP

Repayment from carrying back

£7,950.00

Against profits from 1 April 2024 to 31 March 2025

Loss carried back

£30,000.00

Of £30,000

Loss carried forward

£0.00

Against future profits

Earlier periods

Period	Profit	Loss used	Tax before	Tax after	Repayment
1 April 2024 – 31 March 2025	80,000.00	30,000.00	17,450.00	9,500.00	7,950.00
Total	—	30,000.00	—	—	7,950.00

Estimate only. Assumes 12-month earlier periods ending the day before the loss period starts, no associated companies and no other income in the loss-making period (a loss must be set against that first). The claim is made in the Company Tax Return within two years of the end of the loss-making period.

Guidance only. This calculator gives a general estimate and is not tax advice. Speak to your accountant before relying on these figures or making any decisions based on them.

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

Sources: Corporation Tax: calculating and claiming a loss, Corporation Tax rates and allowances on GOV.UK.

Last updated 11 October 2026.

Need to file the CT600?

This calculator is for guidance only. Tax Optimiser prepares the full corporation tax computation and files the CT600 and accounts with HMRC and Companies House.