Last updated: August 2026 | Figures correct as of publication — always check the provider’s current fee schedule before opening an account
Most SIPP comparison articles are written with a steady saver in mind — someone paying in a fixed amount every month, for decades, without much variation. That’s not how self-employed contributions usually work. You might pay in a lump sum after a strong quarter, skip months entirely during a lean patch, or want to top up in December once you can see the year’s numbers. That changes which fee structure actually suits you — and it’s the piece most generic comparison articles skip.
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Percentage fees vs flat fees — why this matters more for irregular income
SIPP platforms broadly charge one of two ways:
- A percentage of your pot, typically tiered so the rate drops as your balance grows
- A flat monthly or annual fee, the same regardless of pot size
For someone contributing a steady amount, this is mostly a question of “which is cheaper at my pot size.” For someone contributing irregularly, there’s a second factor: percentage-fee providers scale naturally with whatever you pay in, including in years you contribute very little or nothing — you’re never paying a disproportionate fee relative to a small balance. Flat-fee providers charge the same whether you paid in £50 or £15,000 that year, which can feel expensive during a lean year but becomes noticeably cheaper than percentage fees once your pot grows large enough — generally somewhere in the £50,000-£80,000 region, depending on the specific providers being compared.
If your income (and therefore contributions) genuinely varies year to year, it’s worth weighting this more heavily than a standard comparison would.
The providers worth comparing
Vanguard — Among the cheapest options if you’re happy investing in Vanguard’s own fund range specifically. Charges a percentage fee capped at a fixed annual amount, which keeps costs predictable as your pot grows, provided you don’t need funds outside Vanguard’s own range.
AJ Bell — A tiered percentage fee that steps down as your balance increases, eventually reaching very low levels on larger pots. Offers a wide range of funds and shares beyond a single provider’s own range, which suits anyone wanting more flexibility than Vanguard allows.
Interactive Investor — Runs on a flat monthly subscription rather than a percentage fee, across a few plan tiers. This structure tends to become meaningfully cheaper than percentage-based platforms once your pot passes roughly £50,000-£60,000, but is comparatively less attractive on a small or newly-started pot, since you’re paying the same fee regardless of balance.
Hargreaves Lansdown — The largest and most established SIPP provider, with a wide range of guidance and support alongside the DIY platform. Recently reduced its percentage fee, though it remains toward the higher end of the market — the trade-off is typically service and range rather than lowest cost.
Fidelity — A solid, well-established middle-ground option: competitive on cost for a percentage-fee structure, with a broad fund range, and generally considered approachable for less experienced investors.
Freetrade — Charges a flat monthly fee aimed at larger pots, but restricts investments to shares and ETFs only — no traditional managed funds. Only worth considering if you’re already comfortable picking your own investments without fund options.
What actually matters for irregular contributions
Beyond the headline fee, a few things are worth checking specifically because of how self-employed income works:
- Minimum contribution rules — some providers expect a regular direct debit and charge more, or restrict options, for one-off lump sum contributions. Confirm the provider genuinely supports ad hoc, irregular payments before committing.
- Transfer speed and fees, if you’re consolidating old workplace pensions from previous employment — this varies significantly by provider and is worth checking directly if consolidation is part of the plan.
- Drawdown charges — a smaller concern this far out, but some providers charge extra to move into drawdown at retirement while others include it in the standard fee. Worth a glance even years in advance, since switching provider later has its own costs.
A starting point, not a final answer
There’s no single “best” SIPP for every self-employed person — it depends on your current pot size, how irregular your contributions genuinely are, and how much you value fund choice versus simplicity. As a rough starting point: a smaller or newly-started pot generally favours a percentage-fee provider (Vanguard or AJ Bell), while a larger, more established pot makes a flat-fee platform like Interactive Investor worth serious consideration.
Always check the provider’s current, published fee schedule before opening an account — SIPP charges do change, and the figures above reflect what was published at the time of writing.
This article is for general information only and does not constitute financial advice. Fees and terms change — verify current details directly with each provider before deciding. Speak to an FCA-regulated financial adviser if you’re unsure which option suits your circumstances. Some links on this page are affiliate links — see our [editorial policy] for details.