Once ISA and pension allowances are used up, many UK investors turn to a General Investment Account (GIA) — a perfectly ordinary, unwrapped investment account with no special tax treatment of its own. That means Capital Gains Tax (CGT) becomes a genuine, practical consideration whenever fund holdings are sold at a profit, and understanding how it works is essential for anyone holding investments outside a tax wrapper.
What triggers Capital Gains Tax on fund holdings
CGT applies when an asset is disposed of at a profit — most commonly by selling it, but also by gifting it (with some exceptions, such as gifts to a spouse) or otherwise transferring ownership. For fund investors, this typically means selling units in a fund, shares, or an investment trust for more than was originally paid, after accounting for any costs of buying and selling.
Importantly, CGT is triggered by the act of selling (or otherwise disposing of) an asset, not simply by its value rising while still held. An investor whose GIA holdings have risen substantially in value but who hasn't sold anything has not yet triggered a CGT liability — the tax is calculated at the point of disposal, based on the gain realised at that time.
The annual exempt amount
Every individual has a Capital Gains Tax annual exempt amount — £3,000 for the 2025/26 tax year — meaning the first £3,000 of gains in a tax year is entirely free of CGT. Only gains above this amount are taxable. This allowance has been reduced substantially in recent years compared with historical levels, which is one reason CGT has become a more prominent consideration for GIA investors than it may have been in the past.
Current CGT rates on investments
| Taxpayer band | CGT rate on gains above the exempt amount (investments, not property) |
|---|---|
| Basic rate taxpayer | 18% |
| Higher or additional rate taxpayer | 24% |
Which rate applies depends on the investor's total taxable income plus gains for the year — a gain that pushes total income into a higher tax band can mean part of the gain is taxed at the basic rate and part at the higher rate. These rates and thresholds can change, so checking current HMRC figures before making significant disposal decisions is worthwhile.
How gains are actually calculated
The basic calculation is: sale proceeds, minus the original cost of acquiring the asset, minus allowable costs (such as dealing charges), equals the gain (or loss). Where an investor has bought units in the same fund at different times and different prices — as is common with regular monthly contributions — specific "pooling" rules determine the average cost used for calculating the gain on a partial sale, rather than simply matching a sale against the most recent or most expensive purchase.
Using losses to offset gains
If some investments have fallen in value and are sold at a loss, that loss can generally be used to offset gains made elsewhere in the same tax year, reducing the overall taxable gain. Losses can also often be carried forward to future tax years if they exceed gains in the year they're realised, provided they are reported to HMRC, typically via Self Assessment, within a set time limit.
A worked example
Suppose a higher rate taxpayer holds fund units in a GIA originally bought for £20,000, now worth £32,000. They sell the entire holding, realising a gain of £12,000. After deducting the £3,000 annual exempt amount, £9,000 of the gain is taxable. At the higher rate of 24%, this results in a CGT bill of £2,160.
Had this same investor instead sold only part of the holding, realising a gain of £2,500 in that tax year, the entire gain would fall within the £3,000 annual exempt amount and no CGT would be due at all — illustrating how the timing and size of disposals can affect the tax outcome, even for the same overall underlying investment.
Strategies some investors consider to manage CGT
- Spreading disposals across tax years: selling only part of a large holding in one tax year and the rest in a subsequent year, to make use of the annual exempt amount in each year rather than realising the whole gain at once.
- Using ISA and pension allowances first: since gains and income within an ISA or SIPP aren't subject to CGT at all, many investors prioritise using those allowances before building up large positions in a GIA where practical.
- "Bed and ISA": selling GIA holdings and using the proceeds to subscribe to an ISA, moving future growth into the tax-free wrapper (though this itself can trigger CGT on the sale, so it needs to be weighed against the annual exempt amount and current gain position — this is covered in more depth in a dedicated article on the bed and ISA strategy).
- Offsetting losses: realising losses on underperforming holdings in the same year as gains, where this aligns with an investor's overall strategy, to reduce the net taxable gain.
None of these strategies should be pursued purely for tax reasons without also considering the underlying investment merits — decisions driven solely by tax efficiency, ignoring whether the disposal or reinvestment makes sense as an investment decision, can sometimes be counterproductive.
The "same day" and "30-day" matching rules
Where an investor sells and then buys back units in the same fund within a short window, specific anti-avoidance rules — sometimes called the "bed and breakfasting" rules — determine how the disposal is matched against acquisitions for CGT purposes. Broadly, a sale is first matched against any purchases of the same holding made on the same day, then against purchases made within the following 30 days, before finally being matched against the wider historical pool. This means simply selling and immediately rebuying the same fund to realise a loss (or use up the annual exempt amount) while keeping the same position doesn't work in the way an investor might expect, since the rules specifically prevent this straightforward approach.
Fund switches and mergers
Selling one fund and buying a different one is a disposal for CGT purposes, even if the new fund is very similar to the old one — there's no special exemption simply because the investor stayed invested in "the market" broadly. Occasionally, a fund provider merges or restructures a fund without giving investors a genuine choice, and in some circumstances this can be treated differently for CGT purposes than a voluntary sale — this is a technical area worth checking specifically if it arises.
Reporting and paying CGT
CGT on investments is generally reported and paid via Self Assessment, for the tax year in which the disposal took place. Investors who don't already complete Self Assessment for other reasons but who have taxable gains may still need to register and report, so this is worth checking even for those who otherwise have straightforward tax affairs. Keeping clear records of purchase dates, prices, and any costs is essential, since providers don't always retain full historical records indefinitely, particularly across multiple platforms over many years.
Common mistakes to avoid
Assuming reinvested dividends don't affect the calculation
Where an accumulation fund automatically reinvests dividends, those reinvested amounts are typically added to the base cost of the holding for CGT purposes (having already been subject to dividend tax as notional income, where applicable outside an ISA). Investors who forget to account for this can overstate their eventual capital gain and potentially overpay CGT, or understate it and risk a discrepancy with HMRC's own records.
Not keeping adequate purchase records
Because the pooling rules require knowing the cost of each historical purchase, an investor who has bought units in the same fund sporadically over many years, sometimes across different platforms after a transfer, can find it genuinely difficult to reconstruct an accurate cost base if records haven't been kept carefully throughout.
Leaving all disposals to the last minute of the tax year
Attempting to realise gains or losses in the final days of the tax year, without having planned in advance, increases the risk of rushed decisions and can mean market movements in those final days have an outsized effect on the tax outcome compared with a more considered, earlier-planned approach.
Frequently asked questions
Does CGT apply to funds held within an ISA or SIPP?
No — gains within an ISA or SIPP are entirely free of CGT, which is one of the principal reasons those wrappers are generally prioritised before building up significant GIA holdings, where practical given annual contribution limits.
Can a spouse's unused CGT annual exempt amount be transferred?
Not directly, but assets can generally be transferred between spouses or civil partners without triggering CGT at the point of transfer, meaning a couple can, in effect, make use of both partners' annual exempt amounts by transferring part of a holding before it is sold. This is covered in more detail in relation to spousal transfers and GIAs specifically.
Key takeaways
- Capital Gains Tax applies to profits realised when fund holdings in a GIA are sold or otherwise disposed of, not simply when their value rises.
- The annual exempt amount is £3,000 for 2025/26 — the first £3,000 of gains each tax year is entirely tax-free.
- CGT rates on investment gains above the exempt amount are 18% for basic rate taxpayers and 24% for higher or additional rate taxpayers.
- Losses on other investments can generally be used to offset gains, reducing the overall taxable amount.
- Spreading disposals across tax years, and prioritising ISA and pension allowances, are common approaches to managing CGT exposure.
- Always check current HMRC figures, as the annual exempt amount and CGT rates have changed significantly in recent years and may change again.