SIPP Calculator — Self-Invested Pension

A Self-Invested Personal Pension (SIPP) operates under relief at source: you contribute net of basic rate tax and the provider claims 20% from HMRC automatically. Contributing £800 net results in £1,000 gross in your SIPP. Higher and additional rate taxpayers reclaim the extra 20% or 25% through their self-assessment tax return. The SIPP invests across a wide range of assets including funds, shares, ETFs, investment trusts, and commercial property.

Growth projection uses compound interest on regular contributions plus tax relief top-ups. Monthly contributions of £400 net become £500 gross after basic rate relief. At 5% annual growth (net of platform and fund charges), £500/month over 25 years compounds to approximately £298,000. The calculator models different growth scenarios: cautious (3%), moderate (5%), and adventurous (7%) to show the range of possible outcomes.

SIPP access is currently available from age 55 (rising to 57 from April 2028 under the Pension Schemes Act 2021). At access, 25% can be taken as a tax-free lump sum, with the remainder drawn as taxable income via flexi-access drawdown. The calculator models both accumulation phase (contributions + growth) and decumulation phase (drawdown withdrawals), showing projected pot value and sustainable income at your chosen retirement age.

What is a SIPP and how does it differ from a workplace pension? Self-Invested Personal Pension (SIPP) is a DC pension you control — choose your own investments from a wide range (UK and international funds, individual shares, bonds, REITs, even commercial property for premium SIPPs). Workplace pension typically restricts you to 10-20 pre-selected funds. SIPP charges: 0.2-0.45% platform fee on top of fund charges (vs 0.1-0.3% workplace pension). SIPPs suit engaged investors with £20k+ pots wanting more control.

SIPP providers and platform fees. UK market 2026: Hargreaves Lansdown (premium service, 0.45% platform), Interactive Investor (£12/month flat fee — best for £50k+ pots), AJ Bell (0.25% platform), Vanguard Personal Pension (0.15% platform but limited to Vanguard funds — cheapest for under £80k), Bestinvest, Charles Stanley Direct. Pick by: platform fee structure (% vs flat), fund range, mobile app quality, customer service. Easy to transfer between providers if circumstances change.

Investment choices and risk. Typical SIPP allocation by age: 80% equity / 20% bonds for 30-year-olds; 60/40 by age 50; 40/60 by age 65. Low-cost index funds (Vanguard FTSE All-World, iShares Core MSCI World) are typically optimal — beat 80%+ of active funds over 20 years (S&P SPIVA reports). Avoid: individual stocks (concentration risk), high-fee active funds (drag returns), crypto/commodity ETFs in pension (regulatory complexities).

SIPP vs workplace pension — when to add a SIPP. If employer matches up to X% — always contribute X% to workplace first (free money). Then if you have additional saving capacity, a SIPP gives you better investment choice. If you have multiple old workplace pensions from previous employers, consider consolidating into a SIPP for: easier management, better investment choice, lower fees, single point of administration. Don't transfer DB (Defined Benefit) pensions without specialist FCA-regulated advice — almost always worth more in DB form.