Cash Flow Modeller

Cash flow modeller

A simple starting point: enter your numbers and see how your balance moves over time. Not personal advice, an illustration only.

Starting age

Model to age

If you include a spouse below, their employment income periods use their own age. Recurring and one-off expenses still use your age.

Your pots

Cash savings

Instant-access savings held jointly, e.g. an emergency fund. Withdrawals from this pot are never taxed in this model. Drawn on first if income doesn't cover expenses in a given year.

Investments

ISAs and general investments, held jointly. Leave out property and anything you don't plan to draw from. Withdrawals from this pot are never taxed in this model. Drawn on after cash savings are used up.

Monthly investment contribution

The amount you'd like to invest each month from any surplus income. If a year's income doesn't fully cover this alongside your expenses, whatever surplus is available that year is invested instead, and nothing is drawn from cash savings to make up the difference. Any surplus above this amount is added to cash savings.

Contribute until age Ages refer to your age. Leave blank to keep contributing for the whole plan.

Your pension

Any DC pension pot. Each withdrawal is treated as 25% tax-free with the remaining 75% taxed as income, at whatever rate that falls at alongside your other income that year.

Your pension access age The earliest age you can draw from this pension. The UK normal minimum pension age is 55, rising to 57 from 2028. No withdrawals are modelled before this age, even if the pot has funds. Defaults to 55 if left blank.

Your monthly pension contribution

The total going into your pension each month, including your own contribution, any employer contribution, and pension tax relief. This is added straight to your pension pot and doesn't reduce your income or what's available to save elsewhere.

Contribute until age Contributions run from the start of the plan up to this age, then stop, regardless of what income you've entered. Leave blank to contribute for the whole plan.

Include a spouse

Yearly income

Your employment income

Gross, before tax. Ages refer to your age. Add as many periods as you like. Leave "to age" blank if it continues to the end of the plan. For example, £50,000 from age 38 to 55, then £12,500 from age 68 with no end age. The state pension button adds the 2026/27 full new state pension (£12,548 a year) starting at a typical state pension age of 67, edit the "from age" if yours differs.

Increase all employment income above with inflation each year

Yearly expenses

Recurring expenses

Increase these with inflation each year Ages refer to your age. Add as many periods as you like. For example, nursery fees of £14,000 from age 2 to 4 for a child, alongside everyday spending with no end age.

One-off expenses

Ages refer to your age. Add an amount and the age or ages it happens. Separate multiple ages with commas, for example "45, 46, 47, 48, 49" for £10,000 a year over five years.

Or upload a filled-in template

Download a blank template, fill in your settings and a row for every age up to 100, then upload it back here. This replaces the yearly income and expense fields above with your exact figures for each year, so you can be as specific as you like about one-off spending, raises, or a planned drop in income.

Assumptions

Apply income tax to pension withdrawals and employment income

Growth rate on cash

Growth rate on investments and pensions

Cash savings grow at the cash rate throughout. Investments, and each pension up to its own access age, grow at the investments rate.

Growth rate on pensions after access age

Optional. Once a pension is past its own access age, it grows at this rate instead of the investments rate above, reflecting a typical shift to a more conservative allocation once someone can start drawing on it. Applies independently to each person's pension, from their own access age. Leave blank to keep using the investments rate throughout.

Inflation rate

Only used where you've ticked a box above to increase income or expenses with it.

Apply a market shock in one year

Your cash flow, year by year

A simple projection based on the numbers you have entered.

Combined balance at age modelled to

£—

Age money runs out (if it does)

—

All figures are in today's money

Chart

Enter your details to see the chart.

Your age	Spouse's age	Net income	Expenses	Cash	Investments	Pension
Enter your details to see the breakdown.

v18: cash savings and investments are tracked as two separate pots, each with its own growth rate, alongside one or two pensions with monthly contributions (running until an explicit stop age you set) and access ages, each pension optionally switching to a separate, lower growth rate once it's past its own access age. A monthly investment contribution (with its own "contribute until age") is invested each year up to that target, capped at whatever surplus is actually available that year — a shortfall never forces money out of cash savings to hit the target, and in a shortfall year, spending draws from cash first, then investments, then pension. Repeatable income and recurring expense periods, one-off expenses at multiple ages, a one-click state pension add, an optional one-year market shock (which never affects cash), and an optional UK income tax calculation (2026/27 rates) that includes the Personal Allowance taper above £100,000 and employee National Insurance (8%/2%) on employment income. You can also download a year-by-year input template (ages up to 100) and upload it back in as an alternative to the period-based fields, for exact, age-by-age control over income and expenses; uploading a template hides the period-based income and expense fields until it's cleared. Pension withdrawals are never modelled before each person's access age, even if the pot has funds. When a spouse is included, their employment income periods use their own age, tax is calculated separately for each person, and any shortfall drawn from pensions is split between accessible pots in proportion to their available balance. Not modelled: Scottish tax rates, employer National Insurance, and any annual or lifetime pension contribution limits. Any "employment income" entered for ages at or after State Pension age (including amounts added via the state pension button) will still have employee NI applied if it exceeds the NI Primary Threshold, since NI in reality stops at State Pension age but this isn't tracked separately from other income here. Education only, not personal financial advice or a recommendation. Capital is at risk.