Why fund cost is the one factor you can control
You cannot control how markets perform, but you can control what you pay. A 1% annual fee on a £200,000 pot is £2,000 a year, and because that money is no longer invested it compounds against you. Over 25 years the difference between paying 0.15% and 1.15% can wipe out roughly a fifth of your final pot. That is why the lowest-cost pension funds matter so much.
Two numbers make up your total cost: the fund's ongoing charge figure (OCF) and the platform or SIPP fee that wraps around it. A cheap fund on an expensive platform is not cheap. Below we rank the funds purely on OCF; pair them with a low-fee SIPP to get your all-in cost down.
Cheapest UK pension funds in 2026 by OCF
| Fund | OCF (2026) | What it holds |
|---|---|---|
| Fidelity Index World | 0.12% | ~1,500 developed-market shares |
| HSBC FTSE All-World Index | 0.13% | Developed + emerging, ~3,600 holdings |
| L&G International Index Trust | 0.13% | Developed ex-UK equities |
| Vanguard FTSE Global All Cap | 0.23% | ~7,000 large, mid and small caps |
| iShares UK Equity Index | 0.05% | FTSE All-Share, UK only |
| Vanguard LifeStrategy 80% | 0.22% | 80% equity multi-asset blend |
The iShares UK Equity Index is the cheapest single fund at 0.05%, but a UK-only fund is poorly diversified - the UK is barely 4% of world markets. For most savers the small extra cost of a global tracker like Fidelity Index World or HSBC FTSE All-World buys far better diversification.
Cost is total cost - watch the platform
A 0.12% fund inside a SIPP charging 0.45% a year still costs you 0.57%. Percentage-fee platforms hurt larger pots; flat-fee SIPPs such as Interactive Investor (around £155 a year) win once your pot passes roughly £50,000. For smaller pots, a capped percentage platform like Vanguard (0.15%, capped at £375) or AJ Bell can be cheaper.
- Pot under £50k: a capped percentage SIPP plus a 0.12-0.13% global tracker.
- Pot over £100k: a flat-fee SIPP plus the same tracker - your all-in cost can fall below 0.25%.
Active funds rarely justify their cost
It is tempting to pay more for an actively managed fund that promises to beat the market. The evidence is sobering: across most ten-year periods, the large majority of active equity managers underperform their benchmark once fees are deducted, and the few that win in one decade rarely repeat it. A typical active global fund charges 0.75-1.00%, six to eight times more than a tracker, and that gap compounds relentlessly. For a pension you will hold for decades, the certainty of low cost beats the hope of outperformance. If you do want a human touch, confine active funds to a small satellite and keep your core in cheap trackers.
How to check what you are really paying
Your fund's factsheet shows the OCF, but transaction costs inside the fund and platform charges sit elsewhere. Use the provider's costs and charges disclosure - mandatory since the FCA's rules - to see a single pounds-and-pence figure for a year. Compare that across providers before you commit, and re-check it annually, because platform pricing changes and a flat fee that was poor value at £40,000 becomes excellent at £150,000.
Verdict
For the lowest realistic all-in cost in 2026, pair Fidelity Index World or HSBC FTSE All-World (both around 0.12-0.13%) with a flat-fee SIPP. You get global diversification for a fraction of a percent. Compare wrappers in our best value SIPP guide, see the cheaper end of the market in best pension index funds, and model the long-term fee savings with our pension calculator.