Corporation Tax Loss Relief Calculator

1. Trading Losses vs Capital Losses — Two Entirely Different Regimes

One of the most critical distinctions in corporation tax is between trading losses and capital losses. Trading losses (from the company's main business activities) are the most flexible: they can be carried back to the prior year, carried forward against all future profits, or surrendered via group relief. Capital losses (from the disposal of chargeable assets such as shares, property, or equipment) are far more restricted: they can only be offset against capital gains in the same accounting period or carried forward against future capital gains. They cannot be carried back, surrendered as group relief, or offset against trading profits.

Companies sometimes mistakenly try to offset capital losses against trading income — this is not permitted. For property investment companies, losses on rental properties are treated as property business losses (a separate category again), which can be offset against other profits of the same period or carried forward against future profits, but cannot be carried back or surrendered in group relief. Understanding which category a loss falls into before deciding on the relief strategy is essential.

2. The 50% Carry-Forward Restriction — Who It Hits

Since April 2017, companies can carry forward trading losses and offset them against total profits (not just trading profits from the same trade). This was a significant liberalisation. However, a restriction was simultaneously introduced: for companies (or groups) with annual profits exceeding £5 million, no more than 50% of profits above the £5 million threshold can be sheltered by carried-forward losses in any single accounting period.

The £5 million "deductions allowance" is shared across a group — it is not available per company. A group with ten companies still has only a single £5 million allowance, allocated as the group chooses. This means large groups with substantial carried-forward losses can only reduce their CT bill by a limited amount each year, even if historical losses theoretically exceed all future profits. For SMEs with profits consistently below £5 million, the restriction does not apply — losses can be used in full as profits arise.

3. Carry-Back vs Carry-Forward — When to Choose Which

The decision between carry-back and carry-forward should consider: (a) the CT rate in the prior year versus the expected future rate; (b) cash flow — carry-back produces an immediate refund, while carry-forward reduces future bills; (c) certainty — a refund from carry-back is certain, future profits are uncertain.

Example: A company has a £100,000 loss in year 3. Prior year profit: £80,000 at 25% CT. Future projected profits: £50,000/year at 19% (small profits rate). Carry-back option: offset £80,000 of loss against prior profits → immediate refund of £20,000 (£80,000 × 25%). Remaining £20,000 loss carried forward → saves £3,800 in year 4 (19%). Total benefit: £23,800. Carry-forward only: offset £100,000 against future profits → £50,000 saves £9,500 in year 4, £50,000 saves £9,500 in year 5. Total: £19,000. The carry-back is superior here by £4,800 — and provides the cash now. However, if future CT rates are expected to increase (e.g., if the company plans expansion and will be in the 25% band), carry-forward may save more in absolute terms.

4. Group Relief — Immediate Cross-Company Loss Utilisation

Group relief is the most time-efficient mechanism for using losses when a group structure exists. A profitable group company can claim relief against its own profits using losses surrendered by a loss-making group member — in the same accounting period. No need to wait for future profits; the benefit is immediate. The surrendering company must be a UK company (broadly) or have a permanent establishment in the UK for EU law purposes. The claimant and surrendering company must be in the same 75% group throughout the overlapping accounting period.

Group relief operates in real time — HMRC does not require the group to wait until the accounting period ends before making provisional claims. This means a profitable group company can provisionally reduce its CT instalment payments based on anticipated group relief from a loss-making subsidiary, improving group cash flow significantly. The provisional claim is then finalised when both companies file their CT returns.

A payment between the surrendering and claimant company for the group relief is common practice (to avoid a deemed benefit being conferred). Such a payment is treated as neither income nor expenditure in either company's hands for CT purposes, but it must be no more than the actual CT saving achieved.

5. Consortium Relief — For Non-75% Ownership Structures

Where a company does not qualify for full group relief (because common ownership is between 5% and 74%), consortium relief may be available. A company is a consortium member if it owns at least 5% of a consortium company (a company owned 75%+ by its consortium members). Losses can flow between consortium members and the consortium company in proportion to ownership percentages.

Consortium relief is more complex than group relief and subject to anti-avoidance rules. "Link company" structures are used when the consortium member and the consortium company are not directly connected — a UK holding company or other related entity creates the qualifying link. The rules were significantly tightened from 2011 onwards to prevent artificial arrangements, and HMRC scrutinises consortium claims closely. Obtain specialist advice before relying on consortium relief.

6. Terminal Loss Relief — Maximising Relief When Ceasing Trade

When a company permanently ceases trading, any losses in the final 12 months can be carried back three years (instead of the standard one year) against profits of the same trade. The relief is applied against the most recent year first and works backwards. This can generate substantial CT refunds where a company has had several profitable years before its final loss-making period.

Example: A company ceases trading in December 2025 with a terminal loss of £150,000 over its final 12 months. Prior profits: 2024/25 = £80,000 (25% CT = £20,000 paid); 2023/24 = £60,000 (25% CT = £15,000 paid); 2022/23 = £40,000 (19% CT = £7,600 paid). Terminal loss offset: £80,000 against 2024/25 → refund £20,000. £60,000 against 2023/24 → refund £15,000. £10,000 against 2022/23 → refund £1,900. Total refund: £36,900 on a £150,000 terminal loss. Without terminal loss relief, the remaining loss would simply be lost forever. The claim must be made within two years of the final accounting period end.

7. Anti-Avoidance Rules — Loss-Buying and the TAAR

HMRC has extensive anti-avoidance rules targeting the artificial generation or acquisition of losses. The principal provisions prevent companies from acquiring another company primarily for the benefit of its historical losses — often called "loss-buying." Where there is a major change in ownership combined with a major change in the nature or conduct of the company's trade within three years of the ownership change, pre-existing losses are extinguished and cannot be carried forward.

The Targeted Anti-Avoidance Rule (TAAR) in CTA 2010 s.730A also catches contrived arrangements designed to obtain loss relief not intended by Parliament. HMRC actively uses the GAAR (General Anti-Abuse Rule) in abusive schemes. Legitimate commercial loss relief — arising from genuine business downturns, market conditions, or genuine restructuring — is not targeted. The key test is whether the loss relief claim would be "contrary to the principles on which the relevant provisions are based" or would produce results that are "not the intended purpose" of the legislation.