How the planner works
Last updated: 1 September 2026
What this tool is — and isn't
It is software that models your finances so you can explore “what if?” questions for yourself. Every figure it shows is an estimate based on the assumptions you can see and change. It is not financial advice, and it is not a forecast or a guarantee. It cannot know your full circumstances, and real markets, tax rules and life rarely follow a straight line. For a decision that matters, speak to a regulated financial adviser — this tool is designed to help you arrive at that conversation better informed.
How a projection is calculated
The engine runs your plan one year at a time, from your current age to the end age you set. For each year it:
- grows each pot by the return you set for it, after deducting that pot's annual fee;
- adds any contributions you're still making while you work;
- adds guaranteed income due that year — State Pension, defined-benefit pensions, rental or other income;
- works out that year's spending need, then withdraws whatever is needed to cover the rest;
- applies tax to the withdrawal and income (see below); and
- carries the closing balances forward as next year's opening balances.
Spending follows the well-documented “retirement smile”: an active early phase, a slower middle, and later life — you control the percentage for each. By default everything is shown in today's money (real terms), so £30,000 in twenty years means what £30,000 buys now; you can switch to future (nominal) money if you prefer.
Tax
When tax modelling is on, the planner applies UK Income Tax — the personal allowance, including its taper for higher incomes — to taxable income and pension withdrawals, and Capital Gains Tax to realised gains in a general investment account. Tax is worked out per person, so a couple gets two sets of allowances and bands rather than one.
You can set your plan to Scotland, which has its own rates and six bands rather than three. Capital Gains Tax is not devolved, so a Scottish taxpayer's gains are still placed against the UK basic-rate limit — a distinction that is easy to get wrong and that the planner handles for you.
Tax rules change and everyone's situation differs, so treat these figures as a careful estimate rather than a personal tax calculation.
Income tax bands for 2026/27
England, Wales & N. Ireland
| Band | Rate | Up to |
|---|---|---|
| Basic rate | 20% | £37,700 |
| Higher rate | 40% | £125,140 |
| Additional rate | 45% | Above the band below |
Scotland
| Band | Rate | Up to |
|---|---|---|
| Starter rate | 19% | £3,967 |
| Basic rate | 20% | £16,956 |
| Intermediate rate | 21% | £31,092 |
| Higher rate | 42% | £62,430 |
| Advanced rate | 45% | £125,140 |
| Top rate | 48% | Above the band below |
“Up to” is an amount of income above the personal allowance. Sources: GOV.UK — Income Tax rates and GOV.UK — Scottish Income Tax.
The figures we use, and where they come from
Every statutory figure below is read directly from the same place the calculation engine reads it, so this page cannot drift from what the planner actually does. Each one links to its source so you can check it.
| Figure | 2026/27 | How the planner uses it |
|---|---|---|
| Personal allowance | £12,570 | Tapers away by £1 for every £2 of income above £100,000, which the planner applies by default. GOV.UK — Income Tax rates |
| Capital Gains Tax | 18% / 24% | The lower rate applies to gains that fall within your unused basic-rate band, the higher rate above it. Annual exempt amount £3,000. CGT is not devolved, so Scottish taxpayers use UK bands for gains. GOV.UK — Capital Gains Tax rates |
| Full new State Pension | £12,548 a year | £241.30 a week. The planner seeds this figure and lets you change it — check your own forecast on GOV.UK. GOV.UK — Benefit and pension rates |
| State Pension age | 66, 67 or 68 | Worked out from your birth year: 66 for people reaching it now, 67 for most, and 68 for anyone born from 6 April 1978. Where a birth year straddles a cut-off, the planner says so rather than guessing. GOV.UK — State Pension age timetable |
| Pension access age | 55 | Rising to 57 from April 2028. New pensions in the planner default to 57. GOV.UK — Early retirement |
| Lump sum allowance | £268,275 | The total tax-free cash one person can take across all their pensions — separate from the 25%-per-pot limit. The planner tracks both, per person, across the whole projection. GOV.UK — Tax on your private pension |
| Annual allowance | £60,000 | Drops to £10,000 — the money purchase annual allowance — once you flexibly access a pension. The planner warns when a plan exceeds either, rather than capping it: you may have unused allowance to carry forward, which this model does not track. GOV.UK — Tax on your private pension |
| National Insurance | 8% / 2% | Employee contributions run from £12,570 to £50,270, then drop to the upper rate. Employers pay 15% above £5,000. Used only to cost salary sacrifice — see the limits below. GOV.UK — Rates and thresholds for employers |
| Salary sacrifice NIC cap | £2,000 | From April 2029, sacrificed pension contributions above this attract both employee and employer NICs. Income tax relief is unaffected, so your pot is unchanged — the cost falls on your take-home pay. GOV.UK — Changes to salary sacrifice for pensions |
What we model that many calculators don't
Most free retirement calculators apply a flat tax rate to withdrawals and stop there. These are the places that materially change the answer, and where this planner does the longer arithmetic:
- The lump sum allowance. Tax-free cash is limited both to 25% of each pot and to £268,275 across all of your pensions. We track both, per person, across the whole projection.
- Your remaining personal allowance, not a flat figure. The tax-efficient strategy draws pension into whatever is left of your allowance after your State Pension, defined-benefit income and rent have used part of it — recalculated every year, for each person separately.
- Scottish rates, and the fact CGT is not devolved. Six bands for income, UK bands for gains.
- How you actually pay into a pension. Salary sacrifice, net pay and relief at source are not the same: on relief at source the amount leaving your bank is 80% of what lands in the pension. Tell us which you use and we add the difference, rather than silently understating your pot by a quarter.
- Employer contributions, on top of your own, and counted towards the annual allowance.
- Platform and fund fees, per pot, deducted from growth every year so they compound the way they really do.
- Capital Gains Tax at two rates, with the gain stacked on top of your income to decide which applies — not a single flat rate.
- State Pension age from your birth year, rather than assuming 67 for everyone.
- The bridge before your pension unlocks. Retiring before your pension access age means living on ISAs and savings first; the planner shows whether that bridge actually holds.
Where our growth assumptions sit
Returns are entered in real terms — above inflation — which is easy to misread. A “6%” real return is about 8.7% a year in cash terms, so it looks more cautious than it is next to the nominal figures quoted elsewhere.
The Financial Conduct Authority caps the projection rates an authorised firm may show a client at 2%, 5% and 8% a year in cash terms (COBS 13 Annex 2). Those rules do not bind us — we are not authorised and we do not illustrate a specific product — but we hold ourselves to them anyway, because a growth rate above that ceiling flatters the one question this tool exists to answer.
So every assumption we ship sits inside that range, the planner shows you the cash-terms equivalent of whatever you enter, and it tells you plainly if your own figures go above the ceiling. You remain free to model what you like — you will just be told what you are looking at.
Withdrawal strategy
How you draw money changes how long it lasts, because different pots are taxed differently. The default is a tax-efficient strategy that, each year, spends already-taxed cash first, then draws pension up to your unused personal allowance (at 0%), then ISAs, then the general investment account, and only then pension into higher bands — a genuine lifetime-tax saving. You can override this with a fixed order (cash-first, ISA-first, and so on) or your own custom priority.
The “unused personal allowance” part matters more than it sounds. It is what is left of your allowance once your State Pension, any defined-benefit pension and any rent have taken their share — worked out afresh every year, and separately for each person in the plan. A calculator that assumes the whole allowance is free will tell you that you can draw more tax-free than you can.
How “confidence” is measured
The single year-by-year projection assumes a steady average return. Real returns are bumpy, and the order in which good and bad years fall matters. To capture that, the planner runs a Monte Carlo simulation — many randomised return paths around your assumptions — and reports the share of them in which your money lasts the whole plan. That percentage is a measure of resilience to market luck, not a probability of any particular outcome.
Historical stress test
Alongside the simulation, you can replay your plan through real history — actual UK equity returns and inflation for every start year on record — to see how it would have fared through past booms, crashes and inflationary decades. The data is the Jordà–Schularick–Taylor (JST) Macrohistory Database (Release 6), a free, open-access academic dataset (macrohistory.net). Its terms require the following citations:
- Òscar Jordà, Moritz Schularick, and Alan M. Taylor. 2017. "Macrofinancial History and the New Business Cycle Facts." NBER Macroeconomics Annual 2016, volume 31. Chicago: University of Chicago Press.
- Òscar Jordà, Katharina Knoll, Dmitry Kuvshinov, Moritz Schularick, and Alan M. Taylor. 2019. "The Rate of Return on Everything, 1870–2015." Quarterly Journal of Economics, 134(3), 1225–1298.
Spending benchmarks
To help you sense-check a spending figure, the planner labels it against the Retirement Living Standards — the UK's independent benchmark for what a Minimum, Moderate or Comfortable retirement actually costs, published by Pensions UK (formerly the PLSA) and researched by Loughborough University. Figures used are the 2026/27 edition (after-tax, excluding housing costs). See retirementlivingstandards.org.uk.
Key assumptions and their limits
The results are only as good as the inputs and assumptions behind them. In particular:
- investment returns you enter are assumptions, not promises — markets can and do lose money;
- a single inflation rate is applied throughout unless you stress-test with real history;
- tax and pension rules are modelled as at the tax year shown and will change over time;
- we work out your State Pension age from your birth year, but the plan holds your age in whole years, and the statutory boundaries fall on 6 April — so if you were born close to a cut-off it may be a year out. We say so when that applies. Neither the age nor the amount is a DWP entitlement check: get your own forecast;
- National Insurance is not deducted in the projection. We calculate it only to show what salary sacrifice costs you. Pre-retirement take-home is therefore a little optimistic if you have expenses running before you stop work;
- carry-forward of unused pension annual allowance is not modelled, so the allowance warning is a prompt to check rather than a verdict;
- the tax-efficient strategy optimises each year in turn. It does not look ahead across your whole retirement, so it is a sound default rather than a proven lifetime optimum;
- property is treated as illiquid — it grows but is never drawn on automatically; you move it with a one-off event such as a house sale;
- surplus income is not reinvested: money you don't spend in a year doesn't quietly reappear as savings;
- it does not model care-fee caps, means-tested benefits, or Inheritance Tax; and
- it can't account for anything you don't tell it.
Your privacy
The calculation runs entirely in your browser. Your figures aren't sent to a server to be computed, and no account is required to use the planner. Data leaves your device only if you choose to — for example by creating a shareable link, or (on a partner's branded planner) sending your plan to that business. See our Privacy Policy for the full detail.
Who's behind it
Have I Enough? is built and maintained by Codingbadger Creative Limited (company no. 16896863, England and Wales). It is made by Barry Mooring, a software engineer who wanted a clear, honest answer to the question “can I afford to retire?”. Rather than ask you to take the answer on trust, the method is published in full on this page: every assumption, the primary sources behind the UK rules, and the limitations. It is guidance, not regulated financial advice — that stays the job of an FCA-regulated adviser. Questions and corrections are genuinely welcome at support@haveienough.com.
More about us on the About page. Ready to try it? Open the planner, or read the Terms that govern its use.