UK FIRE & ISA-to-SIPP Bridge Calculator
UK pensions are locked until Age 57 (from April 2028). Calculate the exact Stocks & Shares ISA bridge pot you need to fund early retirement before 57, your remaining SIPP target, and how the State Pension at 67 protects your wealth.
⚙️ Retirement Timeline & Wealth
£3,000 / month in today's money.
Retiring at Age 45 requires £348,200 in your ISA bridge to fund expenses until age 57, and £386,300 in your SIPP for life after 57.
100% funded from tax-free Stocks & Shares ISA. Zero access to pension.
25% tax-free lump sum (£268k cap) + remaining 75% drawn under PAYE tax.
+£11,973 State Pension reduces private portfolio drawdown by 33%!
📈 Projected Pot Values at Retirement (Age 45) ISA vs SIPP Growth
| Pot Category | Today's Value | Projected at FIRE Age | Target Required | Readiness Status |
|---|---|---|---|---|
| Stocks & Shares ISA | £120,000 | £405,100 | £348,200 | ✅ Bridge Funded |
| SIPP / Workplace Pension | £180,000 | £471,800 | £386,300 | ✅ SIPP Funded |
The Rule of Age 57: Why UK FIRE Is Different
In the United States, early retirees can access retirement accounts through SEPP 72(t) distributions or Roth conversion ladders. In the United Kingdom, no such loophole exists: pensions are strictly locked until Normal Minimum Pension Age (NMPA), which rises from age 55 to 57 on 6 April 2028.
This creates a mathematical necessity for a Two-Pot Strategy:
- The ISA Bridge Pot: Must be sized exactly to fund all living expenses from the day you hand in your notice until your 57th birthday. It can be completely depleted to £0 at age 57 because the SIPP takes over.
- The SIPP Pot: Continues to compound untouched during your 40s and early 50s. At age 57, you can withdraw up to 25% tax-free (capped at £268,275 Lump Sum Allowance), drawing down the remainder over your lifetime.
Frequently Asked Questions
What happens if my ISA bridge runs out before age 57?
Withdrawing from a registered pension scheme before age 57 triggers HMRC's "unauthorised payment" tax charge of up to 55%, plus potential scheme sanction charges. Ensuring an adequate safety buffer in your ISA pot is crucial to prevent forced early pension withdrawals.
Should I prioritize ISA or SIPP contributions while working?
Higher and additional rate taxpayers receive 40% to 45% tax relief on pension contributions, giving SIPP investing an enormous mathematical edge over ISAs. Most UK FIRE practitioners maximize their pension to capture tax relief, then direct sufficient surplus into their Stocks & Shares ISA to build their required bridge to age 57.