SIP → SWP Calculator — United Kingdom
One timeline for the whole plan: build a pot with regular monthly investing, then turn it into a monthly income — with UK capital gains tax done properly.
Published by GrowThenDraw Editorial Team · Editorial policy · Methodology & sources
The most that portfolio can sustain for the full 30 withdrawal years: £1,732/month before tax.
| Year | Phase | Cash flow | Tax | End balance |
|---|---|---|---|---|
| 1 | Invest | £6,000 | £0 | £6,232 |
| 2 | Invest | £6,000 | £0 | £12,915 |
| 3 | Invest | £6,000 | £0 | £20,082 |
| 4 | Invest | £6,000 | £0 | £27,766 |
| 5 | Invest | £6,000 | £0 | £36,005 |
| 6 | Invest | £6,000 | £0 | £44,841 |
| 7 | Invest | £6,000 | £0 | £54,314 |
| 8 | Invest | £6,000 | £0 | £64,473 |
| 9 | Invest | £6,000 | £0 | £75,367 |
| 10 | Invest | £6,000 | £0 | £87,047 |
| 11 | Invest | £6,000 | £0 | £99,572 |
| 12 | Invest | £6,000 | £0 | £113,003 |
| 13 | Invest | £6,000 | £0 | £127,404 |
| 14 | Invest | £6,000 | £0 | £142,847 |
| 15 | Invest | £6,000 | £0 | £159,406 |
| 16 | Invest | £6,000 | £0 | £177,162 |
| 17 | Invest | £6,000 | £0 | £196,201 |
| 18 | Invest | £6,000 | £0 | £216,617 |
| 19 | Invest | £6,000 | £0 | £238,508 |
| 20 | Invest | £6,000 | £0 | £261,983 |
| 21 | Withdraw | £27,536 | £2,464 | £249,759 |
| 22 | Withdraw | £27,375 | £2,625 | £236,652 |
| 23 | Withdraw | £27,224 | £2,776 | £222,598 |
| 24 | Withdraw | £27,083 | £2,917 | £207,527 |
| 25 | Withdraw | £26,952 | £3,048 | £191,367 |
| 26 | Withdraw | £26,830 | £3,170 | £174,039 |
| 27 | Withdraw | £26,684 | £3,316 | £155,458 |
| 28 | Withdraw | £26,542 | £3,458 | £135,534 |
| 29 | Withdraw | £26,410 | £3,590 | £114,169 |
| 30 | Withdraw | £26,287 | £3,713 | £91,260 |
| 31 | Withdraw | £26,172 | £3,828 | £66,695 |
| 32 | Withdraw | £26,065 | £3,935 | £40,355 |
| 33 | Withdraw | £25,965 | £4,035 | £12,110 |
| 34 | Withdraw | £10,986 | £1,262 | £0 |
Why chain the two calculators?
Running them separately makes you guess the one number that decides your CGT: the cost basis of your pot. Chaining fixes that — the withdrawal phase starts with exactly the pot your investing built and exactly your contributions as its book cost, which is what HMRC's Section 104 average-cost rules tax you on.
Inside a Stocks & Shares ISA all of this is moot — withdrawals are tax-free and the planner will show it. In a general investment account, each year's gains get the £3,000 annual exempt amount and are then taxed at 18% or 24% by band.
A realistic retirement question, answered
"If I put away £500 a month for twenty years, what monthly income does that buy — after tax — and until when?" The chart shows the whole arc: bars rise through the investing years, then fall (or keep rising, if your withdrawal rate is modest) through the drawdown years, turning red only if the pot runs out.
Related reading
Frequently asked questions
Is this the same as pension drawdown?
No — drawdown from a SIPP or workplace pension is taxed as income under different rules. This planner models investing and withdrawing through an ISA (tax-free) or a general investment account (capital gains tax with the annual exempt amount).
How does the calculator know my cost basis?
Because it watched you build the pot: the withdrawal phase carries over your total contributions as book cost automatically. That's the number a standalone SWP calculator forces you to look up or guess.
Which CGT band applies to the withdrawal years?
Enter your annual taxable income after the Personal Allowance and other Income Tax reliefs. The calculator deducts the £3,000 gain exemption, uses any room left in the £37,700 basic-rate band at 18%, and applies 24% above it, so a gain can straddle both rates.
Tax figures for 2026/27 last verified 26 July 2026 against the official source — how we calculate.
GrowThenDraw is not authorised or regulated by the Financial Conduct Authority and does not provide financial advice. All results are educational estimates only — consider advice from an FCA-authorised financial adviser before acting.
Relevant bodies in this jurisdiction: FCA (financial conduct), HMRC (tax).