What is a chargeable event gain? The events, the computations and the timing

An investment bond is not taxed as it grows. Nothing enters the policyholder's tax return until a chargeable event happens — and then a single figure, the chargeable event gain, is charged to income tax. Everything else in the bond family follows from that: top-slicing relief spreads the gain, deficiency relief unwinds part of it, the 5% allowance defers it. This page is the rule the others sit on.

The events

ITTOIA 2005 s.484(1) lists them, and HMRC summarises them at IPTM3400. On a life insurance policy or capital redemption policy the events are: the surrender of all rights; the assignment of all those rights for money or money's worth; the falling due of a sumpayable as a result of a right under the policy or contract to participate in profits, if there are no remaining rights under it (s.484(1)(a)(iii) — an event HMRC's own summary list at IPTM3400 does not carry, so read it from the section); maturity; and, for a life policy, a death giving rise to benefits under it. A life annuity contract adds the death, or the taking of a capital sum as an alternative to annuity payments.

Three further events are treated as arising by other sections: an excess event where the periodic calculation on a part surrender or part assignment shows a gain (s.509(1)); a part surrender or assignment event in the special transaction-based cases (s.514(1)); and a personal portfolio bond event, the annual deemed gain (s.525(2)).

The word doing the most work is for money or money's worth. An assignment by way of gift — into a trust, or between spouses — is not a chargeable event; it moves the future liability to the assignee rather than crystallising one now. That is why an inter-spouse assignment before surrender is a mechanical fact worth checking on any file: it changes who is taxed, not whether there is tax.

ITTOIA 2005 s.484 · IPTM3400 (when events occur: general)

Which computation applies

HMRC sets out three calculation rules at IPTM3500, and the event decides which one runs.

The final-event formula is the one most people picture: total benefit value less total allowable deductions. In the engine's terms — the same arithmetic an insurer runs for a chargeable event certificate — that is (surrender value + previous withdrawals) − (premiums paid + previous excess gains), floored at zero. Deducting the earlier excess gains is what stops the same growth being taxed twice.

The periodic calculation is different in kind. It does not ask what the bond is worth; it asks whether the cash taken out in the insurance year has run past the allowance that has accrued. The allowable element for each premium is the payment multiplied by y/20, where y is the number of insurance years — capped at 20 — from the year the premium was paid through to the calculation year. That is the familiar 5% a year, expressed the way the manual expresses it. Unused allowance carries forward; go past the cumulative figure and the excess is a gain, whatever the bond has actually earned.

IPTM3500 (calculating gains: general) · IPTM3560 (periodic calculations and excess events) · ITTOIA 2005 ss.491–541, ss.507–509

The timing rule that catches people out

An insurance year runs from the policy anniversary to the day before the next one (IPTM3505). It is not the tax year, and it is not the calendar year. The periodic calculation is made at the end of the insurance year, and where it shows a gain the excess event is treated as arising then.

So the tax year a part-surrender gain falls into is the one in which the insurance year ends — not the one in which the money was paid out. Take a £100,000 single-premium bond that started on 12 June 2019, with £45,000 withdrawn on 1 March 2025.

The cash left the bond on 1 March 2025, inside the 2024/25 tax year. The gain is taxable in 2025/26, because that is when insurance year 6 ended. Put it on the wrong return and the figure is right but the year is wrong — which is the version of this error that survives a review, because nothing in the arithmetic looks off.

The mirror case is worth stating too: a withdrawal taken a few days after an anniversary sits in the new insurance year and gets a fresh tranche of allowance, while the same withdrawal a few days earlier does not. The anniversary, not the tax year, is the line that matters.

IPTM3505 (insurance year) · IPTM3560 (periodic calculations and excess events) · ITTOIA 2005 s.509

What the final event then looks like

Carry the same bond forward. It is surrendered in full on 1 October 2028 for £95,000 — less than the premium paid, and yet there is still a gain, because £45,000 has already come out.

Worked-example basis: No time-apportioned reduction is due for any gain or policy shown. TAR is not calculated or applied. Raw gains are shown before any TAR.

Two things to note. The £15,000 already taxed as an excess event is deducted, so the total charged across the life of the bond is £40,000 and not £55,000. And N, the complete-years figure that drives top-slicing relief, is 9 — the number of complete 12-month periods from 12 June 2019 to 1 October 2028. It is date arithmetic from the policy start, “not insurance years” in HMRC's own words at IPTM7560, and it never gets a +1 for the final year.

ITTOIA 2005 ss.491–541 (the gain) · s.536(1) Step 1 and IPTM7560 (complete years) — arithmetic reproducible on the chargeable event gain calculator

Who is taxed, and what happens next

The gain is income, not a capital gain. It is charged on the person who beneficially owns the rights (ITTOIA 2005 s.465) and enters the computation as the top slice of savings income. Where the policy is held by personal representatives, s.466 makes them liable only in the narrow case its subsection (2) describes — where the s.530(1) deemed basic-rate credit would not have been available to an individual; otherwise the gain falls into the aggregate income of the estate. The section fixes no rate of its own: HMRC charges such a gain as savings income at the basic rate (IPTM3240). Where UK trustees are liable under s.467, the one rate that section sets is the savings basicrate, and only in its charitable cases (s.467(7)); the familiar trust rate on other trustee gains comes from ITA 2007 ss.481–482, not from s.467. Top-slicing relief is an individual's relief under s.535, so neither personal representatives nor — outside the bare-trust case — trustees can claim it.

An onshore bond carries a deemed basic-rate credit for the tax paid inside the fund (s.530), so a basic-rate taxpayer often has nothing further to pay. An offshore bond rolls up gross and carries no such credit against the real liability, which is why the same gain costs more. The onshore and offshore positions are compared in onshore vs offshore bonds, and priced by the onshore bond tax calculator and the offshore bond tax calculator.

The common error

Three recur. The first is treating a withdrawal as the taxable event — it is not; the event is the excess thrown up by the periodic calculation, and it is dated to the insurance-year end. The second is running the final-event formula on a part surrender, which ignores the 5% allowance entirely and usually overstates the gain; the engine raises a warning rather than returning that figure silently. The third is forgetting to deduct earlier excess gains at the final event, which taxes the same growth twice.

Build the figure on the chargeable event gain calculator and spread it on the top-slicing relief calculator. The allowance mechanics are worked through in the 5% allowance trap, the choice between routes in part surrender vs segment surrender, the complete-years rule in complete years (N), and the provider paperwork in how to read a chargeable event certificate.

ITTOIA 2005 s.465 · s.466 · s.467 · s.530 · s.535 · ITA 2007 ss.481–482 (the trust rate) · IPTM3240 · IPTM3400 · IPTM3500 · IPTM3505 · IPTM3560