Fidelity ISA and SIPP Fees 2026: The Exact Maths for Every Portfolio Size

Fidelity charges a single percentage-based service fee across both ISA and SIPP, with three tiers:

• Under £25,000: 0.35% with a regular savings plan, or £90/year (£7.50/month) without one
• £25,000–£250,000: 0.35% per year
• £250,000–£1,000,000: 0.20% per year
• Over £1,000,000: 0.20% on the first £1m, nothing above — capped at £2,000/year

The 0.35% tier covers both ISAs and SIPPs identically. There is no premium for holding a pension wrapper. Junior ISAs and Junior SIPPs attract no service fee at all, making Fidelity an outlier for family-oriented investors.

Dealing charges are £7.50 per online trade for shares, falling to £1.50 for regular savings plans and dividend reinvestment. Fund purchases and switches carry no dealing fee — relevant since the platform hosts over 3,000 funds. For investors building portfolios through monthly contributions, the £1.50 dealing rate effectively eliminates transaction drag.

The FCA's consumer duty framework requires platforms to demonstrate value — Fidelity's transparent tiered structure passes that test more clearly than some competitors. No exit fees. No transfer charges. That matters when you run the numbers over a decade.

Additionally, the HMRC ISA rules confirm the £20,000 annual ISA allowance for 2025/26. Fidelity's SIPP accepts contributions from £800 lump sum or £20/month regular, with the government adding basic rate tax relief at 20% automatically — meaning an £800 contribution costs you £640 net.

The platform fee is the same. The tax treatment is not.

In an ISA: contributions come from post-tax income, growth is tax-free, withdrawals are tax-free, and there is no minimum access age. You can draw down tomorrow if needed.

In a SIPP: contributions receive pension tax relief of 20% to 48% (48% for Scottish higher-rate taxpayers under the Scottish rate of income tax), annual allowance is £60,000 (or 100% of earnings, whichever is lower), but access is restricted to age 55 — rising to 57 in 2028 under legislation already on the statute book.

For a 40% taxpayer, every £1,000 invested into the Fidelity SIPP costs £600 net after relief. That effective cost reduction is far more powerful than any platform fee differential. The SIPP is not just a pension — it is a 67% return on day one for a higher-rate taxpayer, before any investment gains.

Where the SIPP genuinely costs more: if you hold exchange-traded investments (shares, ETFs) in an Investment Account rather than a tax wrapper, Fidelity charges no service fee at all on that account. The ISA and SIPP fees are identical, but holding unwrapped shares on Fidelity is actually free of platform charges — a rarely advertised feature that can be used strategically for assets already sheltered from CGT via the £3,000 annual allowance.

For more on ISA strategy across different account types, see our comprehensive ISA guide and pensions hub.

Here is the annual platform cost at each portfolio size, assuming 100% held in funds (no additional dealing charges):

Portfolio	ISA Annual Cost	SIPP Annual Cost	Interactive Investor Flat Fee
£10,000	£35.00 (0.35%)	£35.00 (0.35%)	£143.88
£50,000	£175.00 (0.35%)	£175.00 (0.35%)	£143.88
£100,000	£350.00 (0.35%)	£350.00 (0.35%)	£143.88
£250,000	£875.00 (0.35%)	£875.00 (0.35%)	£143.88
£500,000	£750.00 (0.20%)	£750.00 (0.20%)	£143.88

The crossover point where interactive investor's £143.88/year flat fee becomes cheaper than Fidelity's 0.35%: approximately £41,100. Below that, Fidelity wins on cost. Above it, flat-fee platforms win — by an increasingly wide margin.

At £250,000 — which is the top of Fidelity's middle tier — the cost gap is £731.12 per year in interactive investor's favour. Over 20 years, assuming both fees grow with the portfolio, that difference compounds to a meaningful sum.

The picture changes above £250,000. At £500,000, Fidelity's 0.20% tier kicks in, and the annual fee drops to £750. At £1,000,000, the cap locks in at £2,000. At £2,000,000, Fidelity costs the same £2,000 — an effective rate of 0.10%. Interactive investor's flat fee remains £143.88 regardless, so for portfolios above £1m, it is still cheaper in nominal terms. But for the typical GiltEdge reader building a retirement pot of £300,000–£700,000, the comparison is the critical one.

For a full breakdown of flat-fee vs percentage platforms across all sizes, see our detailed cost comparison.

Here is the calculation most fee comparison articles ignore.

Suppose you have £50,000 in a Fidelity SIPP and you are a 40% taxpayer. The annual platform cost is £175. But the tax relief on contributions means every £600 you invest becomes £1,000 in the SIPP. If you contribute £6,000 net this year (receiving £2,400 in tax relief to top it up to £10,000 gross), the government has effectively subsidised your platform fee 14 times over in that single year.

The SIPP fee is not the story. The tax relief is.

For basic-rate taxpayers, the arithmetic is less dramatic but still overwhelmingly positive. A 20% taxpayer contributing £800 net receives £200 in relief — already exceeding Fidelity's £35 fee on a £10,000 portfolio. According to HMRC's pension tax relief guidance, relief is added automatically by Fidelity as a pension provider operating relief at source — you do not need to claim it via self-assessment unless you are a higher-rate taxpayer claiming the additional relief.

The annual allowance of £60,000 — confirmed by HMRC for 2025/26 — means a high earner systematically using the SIPP alongside the ISA can shelter £80,000 per year from investment tax. That is the real optimisation. Platform fees are secondary.

Access restriction is the genuine SIPP cost: your money is locked until 55 (57 from 2028). For money you may need before then, the ISA wins regardless of fees.

Fidelity wins for:

• Portfolios under £41,000 where its 0.35% undercuts flat fees
• Portfolios over £250,000 where the 0.20% tier activates
• Investors using the regular savings plan (£1.50 dealing rate vs £7.50 one-off)
• Families with children (Junior ISA and Junior SIPP at zero platform charge)
• Investors primarily holding funds rather than shares (no dealing fees on fund trades)
• The current ISA season cashback offer of £300–£3,000 for transfers or deposits by 5 April 2026

Fidelity loses for:

• Portfolios between £41,000 and £250,000 where flat-fee platforms are cheaper
• Active share traders who deal frequently at £7.50 per trade
• Investors who want a single fixed monthly cost for budgeting purposes

AJ Bell sits between the two: its fees are lower than Fidelity's for mid-sized portfolios but higher than interactive investor's flat rate. Vanguard caps at 0.15% but restricts investors to its own fund range — fine if you want simple index funds, limiting if you want access to 3,000+ external funds.

For the full Fidelity platform picture, see our Fidelity personal investing review and our detailed 2026 fee breakdown.

For a 40% taxpayer with £100,000 invested across both ISA and SIPP on Fidelity, the annual platform cost is £350 — £175 per wrapper. That is a rounding error compared to the tax work those two wrappers do.

The Optimizer's approach for 2025/26:

1. Max the ISA first if you are in basic rate tax or need flexible access: £20,000 into a Fidelity Stocks & Shares ISA. No dealing fees on index funds, 0.35% platform cost on up to £25,000 — or the flat £7.50/month if you are not using a regular savings plan and your balance is under £25,000.

2. Contribute to SIPP up to annual allowance: £60,000 gross limit (£36,000 net for a 40% taxpayer after relief, or £48,000 net for a 45% taxpayer). The moneyhelper.org.uk pension calculator confirms the net-of-relief cost for your tax band.

3. Use the investment account for overflow: If you exhaust both wrapper allowances, hold exchange-traded investments in a Fidelity Investment Account with no platform service fee — using your £3,000 annual CGT allowance to crystallise gains tax-efficiently.

4. Review the crossover point annually: As ISA and SIPP balances grow toward £41,000 per wrapper, calculate whether migrating to a flat-fee platform makes sense. The transfer is free — Fidelity charges no exit fees.

This is not complicated. It is methodical. The FCA's investment platform market study showed that most investors never switch platforms despite substantial fee differences. The data is clear. The action is optional. The Optimizer acts.

For a broader view of investment strategies within tax wrappers, see our investing hub.