CoastFIRE is the point at which you can step off the aggressive savings treadmill and let time do the work. Once you have enough invested, compound growth will carry you to your retirement target — whether that is 10, 20, or 30 years away — without you needing to contribute another penny.
For the broader early retirement planning framework, return to the Early Retirement hub.
Calculating Your UK CoastFIRE Number
The formula is simple: CoastFIRE = Target pot ÷ (1 + annual growth rate)^years until retirement
Example Table: CoastFIRE at Different Ages (5% real growth assumed)
| Target at retirement | Years to retire | CoastFIRE number now |
|---|---|---|
| £750,000 at 67 — currently 40 | 27 years | ~£200,000 |
| £750,000 at 67 — currently 45 | 22 years | ~£255,000 |
| £750,000 at 57 — currently 35 | 22 years | ~£255,000 |
| £750,000 at 57 — currently 40 | 17 years | ~£325,000 |
| £500,000 at 57 — currently 40 | 17 years | ~£217,000 |
Once you hit the relevant number, you can stop adding to the pension or investment pot. It will reach the target on its own.
What “Coasting” Means in Practice
After reaching CoastFIRE:
- Stop maximising contributions — you only need to live on your salary, not save aggressively
- Take lower-paid work — if you were pushing for promotions to fund saving, you no longer need to
- Move part-time — reduced income is fine as long as it covers current expenses
- Pursue lower-income passions — the financial future is funded
The key shift: your future is funded. Your income now only needs to serve today.
UK-Specific CoastFIRE Considerations
Pension Lock-In Before 57
If your CoastFIRE savings are inside a pension, you cannot access them until 57 (from 2028). This means CoastFIRE does not give you freedom to live on your investments before that age — only freedom from continuing to invest.
Solution: Build CoastFIRE across both pension AND ISA. The pension coasts to your retirement target; the ISA coasts (or is drawn from) during pre-57 years.
Inflation Adjustment
Use real (inflation-adjusted) growth rates in your CoastFIRE calculation. If nominal returns are 7% and inflation is 2%, use 5% as the real growth rate. Your target pot should also be expressed in today’s prices.
State Pension as CoastFIRE Booster
The State Pension (£11,502/year from 66) reduces how large your private pot needs to be. If your spending target is £25,000/year, State Pension covers £11,502 — you only need £13,498/year from private sources, requiring a pot of ~£337,000 (at 4%) rather than £625,000. This significantly lowers your CoastFIRE number.
CoastFIRE vs BaristaFIRE vs Full FIRE
| Approach | What it means | Income still needed? |
|---|---|---|
| Full FIRE | Portfolio covers 100% of expenses — no work needed | No |
| BaristaFIRE / Semi-retirement | Portfolio + part-time income cover expenses | Yes — some |
| CoastFIRE | Portfolio will grow to target — stop contributing but keep working | Yes — to cover current expenses |
CoastFIRE is the least financially demanding of the three — you still need to work enough to live, but you eliminate the obligation to save aggressively for the future.
Is CoastFIRE the Right Approach for You?
CoastFIRE works best if you:
- Are in your late 20s to mid-40s with a meaningful pot already saved
- Have a secure income that comfortably covers living expenses without requiring additional saving
- Are in a career or job that you are comfortable continuing for income (if not enthusiasm)
It is less suitable if your job is precarious, your employer pension is at risk, or your health means you may need to stop working sooner than planned. In those cases, building a larger ISA bridge alongside the pension coast pot provides more flexibility.
The core principle remains: time is your most powerful financial tool. Starting early and letting compound growth do the heavy lifting is more effective than starting late and contributing aggressively.