Substantial Shareholding Exemption: how UK companies sell subsidiaries tax-free

If your company sells an asset at a profit — a property, goodwill, machinery — it normally pays corporation tax on the gain at up to 25%. But there is one big exception that surprisingly few owner-managers know about: when a company sells shares in another company, the entire gain can be completely exempt from corporation tax. This is the Substantial Shareholding Exemption, usually shortened to SSE (and sometimes called substantial shareholding relief).

For small and medium-sized companies across Medway and Kent, SSE is one of the strongest arguments for putting a group structure in place before a sale is ever on the horizon. In this guide we explain what the exemption does, the conditions in plain English, how different share types — ordinary, preference and redeemable — affect the tests, and the traps to avoid.

Key takeaways

• SSE exempts the whole gain when a company sells shares in a trading company it has a "substantial shareholding" in — no corporation tax at all on that gain.
• It applies automatically. There is no claim, no election and no HMRC clearance needed — if the conditions are met, the exemption applies whether you like it or not (losses are not allowable either).
• The core test is 10% for 12 months. The selling company must have held at least 10% of the ordinary share capital, with matching rights to profits and assets, for a continuous twelve months in the six years before the sale.
• The company being sold must be a trading company (or the holding company of a trading group) — investment activities can spoil it.
• Share classes matter. The 10% test is measured on ordinary share capital, so fixed-rate preference shares are generally ignored — which can help or hurt depending on which side of them you sit.

What the exemption actually does

SSE sits in the corporation tax rules (Schedule 7AC of the Taxation of Chargeable Gains Act 1992, if you want the chapter and verse — HMRC's guidance starts at CG53000). When it applies, the gain a company makes on selling shares is simply not a chargeable gain. Not deferred, not taxed at a lower rate — exempt.

A worked example makes the point. Suppose your holding company sells a trading subsidiary for £2 million, having originally subscribed £100 of share capital. That is a £2 million gain which, without SSE, would suffer corporation tax of up to £500,000. With SSE, the tax on the gain is nil, and the full £2 million lands in the holding company — ready to be reinvested in the next venture, used to buy premises, or paid out over time in a planned, tax-efficient way.

The flip side is worth stating clearly: SSE is a two-edged sword. If the shares are sold at a loss and the conditions are met, that loss is not allowable — you cannot set it against other gains. The exemption is automatic, not optional.

The conditions in plain English

There are two sets of conditions: one about the size and length of the shareholding, and one about what the company being sold actually does.

1. The substantial shareholding test

The selling company must have held a "substantial shareholding" — broadly, all three of the following — for a continuous period of at least twelve months at some point in the six years before the sale:

• at least 10% of the ordinary share capital of the company being sold;
• entitlement to at least 10% of the profits available for distribution; and
• entitlement to at least 10% of the assets on a winding up.

The six-year window is generous and deliberate: it means you can sell your stake in stages, or hold on to a small rump after a main disposal, and later sales can still qualify even though your holding has dropped below 10% by then. Holdings of fellow group companies are added together for the 10% test, which helps groups that spread ownership across more than one entity.

2. The trading condition

The company whose shares are being sold must be a trading company, or the holding company of a trading group, from the start of the twelve-month qualifying period up to the sale. "Trading" here means carrying on trading activities without a substantial level of non-trading activity — HMRC's long-standing rule of thumb is around 20%, looking at income, asset values, expenses and management time in the round.

This is where owner-managed companies most often come unstuck. A trading company that has quietly accumulated a large buy-to-let portfolio, or a substantial pot of surplus cash invested for return, may have drifted over the line into "substantial non-trading activity" without anyone noticing. If a sale is on the cards, it pays to review this well in advance — tidying up often takes more than twelve months.

Since reforms in 2017, the selling company itself no longer needs to be a trading company. That change made SSE far more useful for family and investment-led structures, such as the group arrangements we describe in our guide to holding company benefits.

Why share types matter: ordinary, preference and redeemable shares

The 10% test is measured against ordinary share capital, and that phrase has a specific tax meaning: all the company's issued share capital except shares that carry a right to a dividend at a fixed rate and no other right to share in profits. If share classes are new territory, our plain-English guide to the types of shares in UK private companies walks through them all — but here is how each one interacts with SSE:

• Ordinary shares are the straightforward case: they count in full towards the 10% test, and so do most alphabet shares (A, B, C classes), because they share in profits beyond a fixed rate.
• Preference shares need care. A classic fixed-rate preference share — say, a 6% fixed dividend and nothing more — is excluded from ordinary share capital. That cuts both ways: a company holding only fixed-rate preference shares cannot meet the 10% test on them, but equally, a large slab of fixed-rate preference shares held by an outside investor is ignored when working out whether your holding reaches 10%. Participating or convertible preference shares, which share in profits beyond the fixed rate, generally do count as ordinary share capital — so the drafting of the share rights genuinely changes the tax answer.
• Redeemable shares are judged on their dividend and profit rights, not on the fact they can be bought back — redeemability itself is neutral for SSE. So a redeemable ordinary share, which shares fully in profits, counts towards the 10% test just like any other ordinary share: hold 10% of the company through redeemable ordinary shares for the twelve months and SSE can apply. A redeemable fixed-rate preference share, carrying only a fixed dividend and nothing more, sits outside ordinary share capital, so a stake made up entirely of those can never satisfy the 10% test — no matter how large it is or how long it has been held. Watch the hybrids too: a redeemable preference share that also participates in surplus profits, or converts into ordinary shares, will usually count as ordinary share capital after all. And remember the redemption itself is a separate tax event with its own treatment — SSE only shelters a gain on a disposal of shares by a company that meets the conditions.

Remember too that the 10% test has three limbs. A share class with full dividend rights but watered-down capital rights (or vice versa) can pass one limb and fail another, so growth shares and other bespoke classes need checking against all three.

Where SSE fits for an SME: the group structure play

SSE only works when a company sells the shares. If you hold your trading company personally and sell it, you are in capital gains tax territory — potentially with Business Asset Disposal Relief, but on your own shoulders. The classic structure that unlocks SSE looks like this:

• You own a holding company;
• the holding company owns one or more trading subsidiaries;
• when a subsidiary is sold, the holding company banks the proceeds free of corporation tax under SSE.

The proceeds can then fund the next acquisition, buy the trading premises, or be drawn down gradually as dividends timed around your personal tax position. For serial entrepreneurs and family businesses building more than one venture, this is usually a far better outcome than selling shares personally each time. Getting an existing standalone company into this structure is normally done by a share-for-share exchange, which has its own clearances and conditions — this is planning to do early, not the month before a sale. Our holding company guide covers the wider pros and cons.

Common traps

• Selling too soon. A newly formed holding company must clock up its twelve-month qualifying period. Special rules can help where a new subsidiary receives a trade previously carried on within the group, but do not assume — check.
• Non-trading drift. Surplus cash, investment property or loans to connected parties inside the target company can breach the trading condition. Review well before marketing the business.
• Assuming losses are allowable. If SSE conditions are met on a loss-making disposal, the loss disappears. Occasionally it is worth deliberately failing a condition to preserve a loss — specialist advice territory.
• Muddling SSE with personal reliefs. SSE is a corporation tax exemption for companies. It does not reduce the tax you pay personally when money is later extracted from the holding company — that is a separate planning exercise.
• Forgetting the paperwork. No claim is needed, but HMRC can and does ask for evidence of the trading status and the shareholding history. Keep board minutes, statutory registers and accounts that tell the story.

Talk to us before you restructure or sell

SSE rewards companies that plan ahead. Whether you are thinking about inserting a holding company, tidying up share classes, or preparing a subsidiary for sale, the earlier the structure is reviewed the more options stay open. Professional Trust Group advises owner-managed companies across Rochester, Medway City Estate and the wider Kent area on group structures, share reorganisations and business sales — book a free consultation and we will tell you honestly whether SSE planning is worth it for your business.

This article is general information, not advice. The Substantial Shareholding Exemption rules are detailed — see HMRC's guidance at CG53005 onwards — and every structure should be reviewed on its own facts before acting.