Value is not the same as cheapest
A SIPP's value comes from its total cost of ownership weighed against the choice, tools and service you actually use. A platform with a rock-bottom headline fee but a narrow fund range may be poor value if it forces you into expensive in-house funds. The genuinely best-value SIPPs combine low platform charges, cheap dealing and access to low-cost index funds.
| SIPP | Platform fee | Fund dealing | Annual cost on £50k |
|---|---|---|---|
| Vanguard SIPP | 0.15% (cap £375) | Free | £75 |
| AJ Bell SIPP | 0.25% | £1.50 funds | £125 |
| interactive investor SIPP | £12.99/mo flat | Free regular investing | £156 |
| Hargreaves Lansdown SIPP | 0.45% (cap £200 shares) | Free funds | £225 |
| Fidelity SIPP | 0.35% | Free funds | £175 |
How pot size changes the answer
On a £50,000 pot, Vanguard's £75 a year is unbeatable for value. On £150,000, interactive investor's fixed £156 beats AJ Bell's £375 and HL's £675. By £500,000, ii's flat fee is dramatically better value than any percentage charger — the saving runs into thousands a year. The trick is to recalculate as your pot grows and switch when the maths flips.
Don't forget fund costs
The platform fee is only half the picture. Pairing a cheap platform with a low-cost global tracker such as the Vanguard FTSE Global All Cap (0.23%) or HSBC FTSE All-World Index (0.13%) keeps your total cost low. A 0.15% platform fee is undone if you buy a 1.5% actively managed fund inside it.
Verdict
For value, Vanguard wins for smaller pots, AJ Bell is the best all-rounder, and interactive investor is unbeatable once your pot is six figures. See the full field in our best SIPP providers guide, estimate your future pot with our pension calculator, and check fund options in our best pension UK guide.