Every allowance that resets on 6 April, what each one is worth to you, and how long is left to use it. Use-it-or-lose-it items first.
On the figures so far
2 actions still open, worth about £990 in total. 203 days until 5 April.
Every figure came from you, and the gap is £450 — well outside rounding.
Refine it in 7 questions below.
The decision
2 actions still open, worth about £990 in total. 203 days until 5 April.
£450 better than use the rest of your isa allowance, on the same figures.
Each of these has to be true. Where your answers settle it we have said so; where they cannot, the test is yours to check.
The tax year has not ended. — we cannot tell from your answers
ITA 2007 s. 4 — the tax year runs 6 April to 5 April
For the ISA allowance: you are 18 or over and UK resident. — we cannot tell from your answers
ISA Regulations 1998, reg. 10
For pension carry-forward: you were a member of a registered scheme in the years you are carrying from. — met, on your answers
FA 2004 s. 228A
For the CGT exempt amount: you have gains you could realise. — met, on your answers
TCGA 1992 s. 1K
For Marriage Allowance: one of you earns under the personal allowance and the other is a basic-rate taxpayer. — we cannot tell from your answers
ITA 2007 s. 55B
This is information, not tax or financial advice. It shows how the rules apply to the figures you entered — it does not know the rest of your circumstances. Worth checking with an accountant before you act.
Rates as at 6 April 2026 — the 2026/27 tax year.
The figures above are only as good as what sits behind them. These are the records HMRC would ask for.
| When | What | If you miss it |
|---|---|---|
| 5 April | ISA subscriptions, pension contributions, CGT disposals, and any Gift Aid intended for this year. | None of these carry forward except unused pension allowance. The ISA allowance and the CGT exempt amount simply disappear. |
| Late March in practice | Anything needing a transfer to clear or a trade to settle. | The date that counts is when the money reaches the provider or the trade executes, not when you instructed it. Providers publish their own cut-offs, usually several working days earlier. |
| 31 January after the tax year | File the return, pay the balance, and make any Gift Aid carry-back election. | The carry-back election cannot be made on a late return or by amendment. |
| 60 days after completion | Report and pay CGT on a UK residential property disposal. | Penalties from day 61, separate from and in addition to the Self Assessment return. |
| 5 April, four years after | Backdate Marriage Allowance and claim missed reliefs from earlier years. | Out of time — this is the window that makes a first check worth several times the annual figure. |
Resets, gone on 6 April: ISA allowance, CGT exempt amount, dividend allowance, the annual IHT gift exemption. Carries forward: unused pension annual allowance, three years. Backdates: Marriage Allowance and most reliefs, four years.
An unused allowance is only worth the tax it would have saved. £20,000 of ISA allowance is worth nothing if you have no money to put in it, and the CGT exempt amount is worth nothing without a gain.
This year's allowance is used first, then carried-forward allowance oldest first. The oldest year is the one about to expire, so a large contribution can rescue it.
www.gov.uk/guidance/check-if-you-have-unused-annual-allowances-on-your-pension-savings
Selling and rebuying the same holding within 30 days does not work — the share matching rules match the purchase to the sale. Rebuying inside an ISA, or in a spouse's name, does.
Bank transfers, provider processing and settlement all take days. Aim for the third week of March, not the first week of April.
Three situations, worked through. They use the same rules as the tool above, so you can check the arithmetic against a case near your own.
Pension first up to the threshold, because that is where the 40% relief is, then the ISA for the rest. The ISA allowance is large enough that it is rarely the binding constraint.
The exempt amount is small but it is annual and it never carries forward, so realising into it every year is worth more over time than any single action here.
The first £2,000 is worth half as much again as the next £4,000, because it is the part inside the taper. Order matters more than amount.
Every figure above comes from one of these. Where we have interpreted rather than calculated, the tool says so.
The tax year runs from 6 April to 5 April, and allowances are assessed by tax year.
The ISA allowance is £20,000 across all ISAs and does not carry forward.
The CGT annual exempt amount is £3,000 and cannot be carried forward or transferred.
Unused pension annual allowance carries forward three tax years, used oldest first.
Share matching rules match a disposal to any acquisition of the same class within the following 30 days.
Transfers between spouses and civil partners are on a no gain, no loss basis.
The ISA allowance, the CGT annual exempt amount, the dividend and savings allowances, and the £3,000 annual inheritance tax gift exemption. Unused pension annual allowance is the main exception: it carries forward three years.
For this year's allowances, yes. But reliefs you have already earned and not claimed — higher-rate pension relief, Marriage Allowance, employment expenses — backdate four years, and those are usually worth more than the allowance you missed.
Whichever gives the higher relief on the pound in question, then the other. For a higher-rate taxpayer with income near a threshold, the pension is worth 40% or 60% on the part that clears it; beyond that the choice is about access rather than tax.
Not directly — the 30-day rule matches the repurchase to the sale and cancels the gain. Rebuying inside an ISA, inside a pension, or in a spouse's name all work, because they are different holders or different wrappers.
Whatever your provider says, minus the time your bank takes. Most platforms publish cut-offs in the last week of March. Treating 5 April as the deadline is how people miss it.
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