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Advanced Taxation (UK) · Corporation tax: chargeable gains for companies

Substantial Shareholding Exemption (SSE) for Companies in ACCA ATX

Updated 11 October 2026 · Fact-checked

The substantial shareholding exemption (SSE) makes a company's gain on selling shares exempt, and any loss not allowable. The company must hold at least 10% for a continuous 12 months in the last 6 years. The investee must be a trading company or trading group holding company, with non-trading activity not substantial (commonly over 20%).

Understand Substantial Shareholding Exemption

When a company sells shares, the gain is normally a chargeable gain taxed in corporation tax. The substantial shareholding exemption (SSE) removes that charge in the right circumstances. It is automatic, not a claim. You cannot choose to opt out.

The idea is simple. A company that has a substantial stake in a trading business is treated as owning that business, not as an investor. Selling the stake is then not taxed as a gain. The price of this is that losses are not allowable either. So SSE is good for gains and bad for losses.

There are three sets of conditions: the investing company (the seller), the company invested in (the one whose shares are sold), and the holding. The detailed conditions are in the key rules below. Learn them as a checklist and test each one against the facts in the question.

If SSE applies, the gain or loss is simply left out of the corporation tax computation. If any condition fails, you compute the gain in the normal way using the share pooling rules and tax it in the company's profits. Do not apply SSE just because the holding is large. Check every condition.

Examiners often combine SSE with planning. You may be asked to compare selling shares with selling the underlying assets, or to advise whether a loss would be better realised before the conditions are met. Always say what the answer means in tax terms.

Key rules to remember

Effect of SSE
Gain on disposal = exempt; loss on disposal = not allowable
Applies automatically when all conditions are met. There is no claim and no election to disapply it.
Investing company (seller) condition
Since 1 April 2017 the investing company need not be a trading company or a member of a trading group
The seller's own trading status is no longer a condition. Do not test it. The trading test now applies to the investee.
Holding condition
Holding of at least 10% of ordinary share capital, with matching entitlement to profits and assets on a winding up, for a continuous 12 months in the 6 years before the disposal
The 12 months need not be immediately before the sale. Holdings can be counted across group members.
Investee company condition
Investee must be a trading company or the holding company of a trading group or subgroup, throughout the 12-month holding period and immediately after the disposal
Non-trading activities must not be substantial (commonly taken as more than 20% of activities). A property investment or investment holding company will not qualify.
Where SSE fails
Gain = disposal proceeds − allowable cost (pool) − indexation allowance (frozen at December 2017); taxed in total profits at the corporation tax rate
Indexation allowance is frozen at December 2017. It is only available on assets held at that date, and only for the period up to December 2017. Use the normal company share pooling and matching rules. Losses are then allowable against chargeable gains.

How to solve Substantial Shareholding Exemption questions

Use this checklist in order. Show each test in your answer so the marker can award a mark for each point.

  1. 1Identify the seller and the shares sold. Confirm the seller is a company and note the percentage held and the dates it was acquired.
  2. 2Test the holding: at least 10% of ordinary share capital, with the matching rights to profits and assets, held for a continuous 12 months in the 6 years before the sale.
  3. 3Test the investee: is it a trading company, or a holding company of a trading group or subgroup, throughout the 12-month holding period and immediately after the sale? Non-trading activity must not be substantial (commonly taken as more than 20%).
  4. 4State the result: if both tests are met, the gain is exempt or the loss is not allowable. If either test fails, say which one and why.
  5. 5If SSE fails, compute the gain using the share pool and add it to total profits. Apply the corporation tax rate stated in the tax tables or question.
  6. 6Add the planning point: for example, wait until 12 months have passed, or note a loss would be allowable only if SSE does not apply.

Quickest way: Two-test scan

When to use it: When the question gives a short scenario and asks whether a gain is taxable.

  1. Holding: 10% and 12 months within 6 years? Write the dates.
  2. Investee: trading company or trading group holding company? Look for any large investment or property activity.
  3. Both pass: exempt gain, no allowable loss. One fails: normal chargeable gain or allowable loss.
  4. Spend your marks on the reason for each test, not on any gain calculation if SSE applies.

Common mistakes in Substantial Shareholding Exemption

  • Treating SSE as a relief that must be claimed

    Other reliefs such as rollover relief need a claim, so students assume SSE does too.

    Fix: State that SSE applies automatically when the conditions are met and cannot be disapplied.

  • Forgetting that losses are not allowable under SSE

    Students focus on the exempt gain and miss the other side of the rule.

    Fix: Always write both effects: gain exempt, loss not allowable. If a loss is expected, consider whether SSE applies.

  • Requiring the 12 months to end on the date of sale

    Students mix this up with other holding-period tests.

    Fix: The 12 months can fall anywhere in the 6 years before the disposal.

  • Applying SSE to an investee that is an investment or property company

    A 100% holding looks strong, so the trading test is skipped.

    Fix: Test the investee's activities. It must be a trading company or the holding company of a trading group, before and immediately after the sale.

  • Saying SSE applies to individuals selling shares

    Students recall the 10% holding and the word 'exemption' without checking who the seller is.

    Fix: SSE is a corporation tax rule for companies. Individuals use CGT rules, including business asset disposal relief where relevant.

Worked examples

Example 1

Alpha Ltd bought 30% of the ordinary shares in Beta Ltd, a trading company, on 1 March 2023 for £480,000. It sold all of the shares on 15 September 2026 for £900,000. Beta Ltd was a trading company throughout and is a trading company at the sale date. Explain the corporation tax treatment of the sale.

Show the solution
  1. Holding: Alpha held 30%, which is at least 10%, and the shares were held from 1 March 2023 to 15 September 2026, which is more than 12 months.
  2. The 12-month period falls within the 6 years before sale, so the holding condition is met.
  3. Investee: Beta was a trading company throughout the holding and is a trading company when the shares are sold, so this test is met.
  4. Both conditions are met, so SSE applies automatically.
  5. The gain would have been £900,000 − £480,000 = £420,000, but it is exempt.

Answer: The £420,000 gain is exempt under SSE and no corporation tax arises. Any loss would have been not allowable.

Example 2

Gamma Ltd bought 8% of the ordinary shares in Delta Ltd, a trading company, on 1 January 2026 for £200,000. It bought a further 12% on 1 April 2026 for £260,000, so it then held 20%. It sold all 20% on 30 June 2026 for £350,000. Advise on whether SSE applies and what the tax result is if it does not.

Show the solution
  1. Holding size: the 8% bought on 1 January 2026 is below 10%, so it does not meet the 10% test on its own.
  2. The holding first reached 10% or more on 1 April 2026, when the further 12% was bought and the total became 20%.
  3. Time: from 1 April 2026 to 30 June 2026 is 3 months, which is less than 12 months.
  4. There is no earlier period of 12 months at 10% or more in the previous 6 years, so the holding condition fails.
  5. Because SSE does not apply, the sale is a normal disposal. The pool cost is £200,000 + £260,000 = £460,000.
  6. Loss = proceeds £350,000 − pool cost £460,000 = £(110,000). No indexation arises because the shares were bought after December 2017.
  7. The loss is allowable as a capital loss and can be set against chargeable gains of the same period or carried forward.

Answer: SSE does not apply because the 10% holding has been held for only 3 months. The £110,000 loss is an allowable capital loss, relieved against chargeable gains.

Exam tips

  • Write the tests in a list and tick them off with the dates from the question. This earns method marks even if you misjudge one fact.
  • Check the sale date and the acquisition dates. A holding that is just short of 12 months is a classic trap, and the answer may be to delay the sale.
  • If a loss is likely, consider whether SSE would remove loss relief. Say so, and advise on whether the conditions can be avoided or the timing changed.
  • Link to the trading test: read the scenario for large investment or property activities in the investee. Non-trading activity above about 20% is commonly taken as substantial. State the effect on the conclusion.
  • Give a clear conclusion in one sentence: exempt gain, or taxable gain or allowable loss.

Practice questions from Corporation tax: chargeable gains for companies

Substantial Shareholding Exemption in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Substantial Shareholding Exemption: frequently asked questions

What are the SSE conditions in ATX-UK?

The company must hold at least 10% of the investee's ordinary shares, with matching profit and asset rights, for a continuous 12 months in the 6 years before the sale. The investee must be a trading company or the holding company of a trading group or subgroup, with non-trading activity not substantial (commonly over 20%). Since 1 April 2017 the seller does not need to be a trading company or group member.

Do I have to claim SSE?

No. SSE applies automatically if the conditions are met. You cannot choose to have the gain taxed so that a loss could be used, because a loss is also not allowable.

Does the 12-month holding have to be just before the sale?

No. It can be any continuous 12-month period in the 6 years before the disposal. This helps where a holding has been reduced over time.

What happens if SSE does not apply?

The sale is taxed as a normal chargeable gain using the company share pooling rules. A loss would be an allowable capital loss. The gain is part of total profits and taxed at the corporation tax rate given in the question.