Lean
Spending is stripped back on purpose. It fails when the stripping was a mood and the boiler, the train fare, or a parent’s care was not in the spreadsheet.
Guide · 4 September 2026
Coast FIRE, said in pounds.
Coasting means the pot you already have could grow to a later target without new contributions, if the return you typed in actually happens. It does not mean you can resign on Friday. It means the saving rate might ease, or a smaller job might be enough, while the existing money is left alone.
Four labels, then we drop the labels
Coast
Contributions can stop because compounding is assumed to finish the job by a traditional age. You still need wages or savings for the years between now and that age.
Barista
Part-time work covers bills. Investments are tapped lightly or not at all. In Britain the useful version includes keeping an employer pension match if the smaller job still offers one.
Fat
A large pot and a large life. Fees, tax, and concentration risk matter more, not less. We do not write shopping lists for it.
One fictional sum, shown in full
A made-up reader is 42 and wants £500,000 in today’s money at 67. That is 25 years. They assume a 4% real return, meaning a return after inflation and before the tax and fees a real account will charge. The pot required today is the target divided by 1.04 to the power of 25.
1.04 to the power of 25 is about 2.666. £500,000 divided by 2.666 is about £187,600. If they already have that much invested, and the return arrives smoothly every year, new contributions are not what gets them to the target. Smooth returns are the part real markets refuse to sign.
If they have £80,000, they are not coasting under these assumptions. They still need contributions, or a lower target, or a later date, or a higher return they should not casually type in to make the discomfort go away.
Change the sketch
Figures stay on this page. We do not store them. A real return can be worse than the one you type, for a long time, at the start. That is why a coasting number is a conversation, not a resignation date.
The 4% rule is American history
Research often cited as “the 4% rule” looked at past US portfolios and a 30-year retirement. A longer UK retirement, with fees, tax on the way out, and a State Pension arriving in the middle, is a different sum. Some writers use 3% to 3.5% as a more cautious starting point for long horizons. None of those numbers is a guarantee you can invoice.
Housing changes the target
A paid-off home in Glenrothes and a rented flat in London are not the same retirement. Do not “count the house” twice: once as a place to live and again as if it were a pension pot you can spend without moving.
The State Pension is the quiet co-author
If a full new State Pension covers a slice of spending from 67, the pot only has to cover the rest, plus the years before 67. Ignoring it makes the target scarier. Treating it as certain before you have checked the forecast makes the target fictional.