Interactive Investor Fees 2026: Core, Plus, or Premium — The Exact Maths Across £50k, £150k, and £500k

Every ii plan bundles ISA, SIPP, and Trading Account access into one monthly fee. There is no separate pension charge — a structural feature that quietly saves SIPP holders up to £156 a year versus platforms that levy a separate SIPP admin fee. All numbers are verified against ii's charges page as of late June 2026.

Core — £5.99/month (£71.88/year)

• Portfolio limit: up to £100,000 across all accounts
• Fund trades: £3.99 each
• UK/US share and ETF trades: £3.99 each
• Other international shares: £9.99 each
• FX charge: 0.75%
• Regular investing: free
• Dividend reinvestment: £0.99 per holding
• No Junior ISA, no family accounts
• Pension admin fee: included in the £5.99

Plus — £14.99/month (£179.88/year)

• Portfolio limit: none
• Fund trades: £1.49 each
• UK/US share and ETF trades: £3.99 each
• Other international shares: £7.99 each
• FX charge: 0.75% on first £50,000, 0.25% above
• 1 free monthly trade (£3.99 credit)
• 5 free family accounts including Junior ISAs
• Pension admin fee: included

Premium — £39.99/month (£479.88/year)

• Portfolio limit: none
• Fund trades: free
• UK/US share and ETF trades: £2.99 each
• Other international shares: £5.99 each
• FX charge: 0.25% flat
• 2 free monthly trades (£5.98 credit)
• Unlimited free family accounts
• ii360 advanced trading platform (expected late 2026)

No platform fee scales with your portfolio. No exit fees, no transfer-in fees, no withdrawal fees. The flat-fee structure is designed to undercut percentage-fee rivals at scale — and at scale it is now widening its lead.

The platform cost conversation has shifted since this article first ran in March. Three numbers from late June 2026 reframe the arithmetic:

• Bank Rate at 3.75% — the Bank of England held at 3.75% since December 2025 after a cutting cycle that brought the base rate down from 5.25%. With Starmer's resignation on 24 June 2026 throwing fiscal policy into uncertainty, the next move is anyone's guess. Cash returns are compressing, which makes the opportunity cost of high platform fees bite harder. A 0.35% custody charge now eats nearly 10% of the yield on a 10-year gilt.

• UK GDP contracted 0.1% in April 2026 — the ONS reported the economy is being held back by the Iran war's impact on global supply chains and energy costs. In a low-growth environment, fee drag compounds more aggressively against subdued nominal returns.

• 10-year gilt yields at 4.94% — the risk-free rate is high enough to make a flat-fee platform's cost advantage over percentage-fee rivals look like real alpha. At £500,000, the £1,426 annual saving from ii Plus versus HL is the equivalent of 28 basis points of return — more than most active managers deliver net of fees.

This is not a call to time the market. It is a reminder that in a low-return, high-uncertainty environment, costs are one of the few variables you control. For more on the broad platform landscape, see our best S&S ISA platforms comparison.

The £50,000 portfolio is the testing ground for whether ii's flat fee beats percentage rivals at the size most UK investors realistically reach. Assume the standard retail mix: £40,000 across five funds and £10,000 across two ETFs. Six trades a year — four fund switches and two ETF top-ups.

Using each platform's published late June 2026 charges:

• ii Core: £71.88 platform fee + (6 × £3.99) = £95.82/year
• AJ Bell: £40,000 × 0.25% funds custody = £100 + £10,000 × 0.25% shares custody = £25 + (4 × £1.50 fund deals) + (2 × £5.00 share deals) = £141.00/year (per AJ Bell charges)
• Fidelity: £40,000 × 0.35% funds custody = £140 + £10,000 × 0.35% shares = £35 (under £90 cap) + (4 × £0 fund trades, free) + (2 × £7.50 share trades) = £190.00/year (see our Fidelity fees breakdown)
• Hargreaves Lansdown: £40,000 × 0.35% funds custody = £140 + £10,000 × 0.35% shares = £35 (under £150 cap) + (4 × £1.95 fund deals) + (2 × £6.95 share deals) = £196.70/year (per the HL March 2026 pricing, unchanged as of June)

ii Core beats AJ Bell by £45/year and HL by just over £100. Fidelity's 0.35% custody rate makes it pricier than AJ Bell for this portfolio, but its free fund trading partially offsets — for investors making frequent fund switches, Fidelity can beat AJ Bell despite the higher custody rate. Over ten years, the ii-versus-HL gap is £450-£1,000 of compounded fee saving — meaningful, not transformative.

But the gap shifts as the portfolio mix changes. Pure-funds investors lose more to percentage fees. Pure-share investors with HL's £150 share custody cap can actually pay less at HL than at ii Core. For a £50,000 portfolio entirely in ETFs and shares, HL's annual cost is £150 (capped) + dealing = roughly £164, which is still more than ii Core's £96 but close enough that trading frequency becomes the tiebreaker. Fidelity's £90 share cap makes it competitive for share-only portfolios at this size — £90 + (6 × £7.50) = £135, closer to ii Core than either HL or AJ Bell.

Flat fees beat percentage fees once portfolios pass critical thresholds. Below those thresholds, percentage-fee platforms cost less. Here is where each crossover sits in late June 2026.

ii Core (£71.88/year) vs AJ Bell (0.25% on funds): breakeven at £28,752. Below that, AJ Bell is cheaper for fund holders.

ii Core vs HL (0.35% on funds): breakeven at £20,537. Pure-fund holders below this number pay less at HL despite the higher headline rate, because ii Core's £71.88 floor exceeds HL's percentage take.

ii Core vs Fidelity (0.35% on funds): breakeven at £20,537 for pure funds — same maths as HL. But Fidelity's free fund trading shifts the comparison for active investors. An investor making 12 fund trades a year saves £47.88 in dealing costs at Fidelity vs ii Core, moving the effective breakeven to ~£34,000.

ii Plus (£179.88/year) vs AJ Bell (0.25% on funds): breakeven at £71,952 — well below the £100,000 Core ceiling, so the moment ii forces you onto Plus, you are already past the AJ Bell crossover.

ii Plus vs HL (0.35% on funds): breakeven at £51,394. Plus pays back almost immediately for fund-heavy investors over £52,000.

ii Plus vs Fidelity (0.35% on funds, £90 share cap): breakeven at £51,394 for pure funds. However, Fidelity's free fund trading and £90 share cap create a competitive zone around £80,000-£150,000 for mixed portfolios where the dealing savings narrow the gap to under £50/year. Our Fidelity review covers this trade-off in detail.

The share-cap inversion: HL's £150-per-account share cap means that if your ISA holds £42,857+ in shares (0.35% × £42,857 = £150), HL stops scaling. A £200,000 share-only ISA at HL costs £150 + dealing — cheaper than ii Plus's £179.88 plus £3.99 share trades. Fidelity's £90 share cap creates the same dynamic at ~£25,714 — and with free fund trading, Fidelity can be genuinely cheaper than ii for active investors with large share holdings.

For a comprehensive breakdown of flat-fee versus percentage-fee platforms across every portfolio scenario, see our full fee comparison. The simple rule: ii wins when you hold mostly funds; percentage platforms with share caps often win when you hold mostly individual shares and trade rarely.

Above £100,000 you are forced onto Plus, so the relevant comparison is ii Plus versus the percentage rivals. The flat-fee advantage compounds aggressively at scale.

£150,000 portfolio (£120k funds, £30k shares/ETFs, 6 trades a year):

• ii Plus: £179.88 + (4 × £1.49) + (2 × £3.99) − £47.88 free-trade credits = £145.94/year
• AJ Bell: £120,000 × 0.25% + £30,000 × 0.25% (under £42 cap) + £16 dealing = £391.00/year
• Fidelity: £120,000 × 0.35% + £30,000 × 0.35% = £105, capped at £90 + (4 × £0 fund trades) + (2 × £7.50) = £525.00/year
• HL: £120,000 × 0.35% + £30,000 × 0.35% (£105, under £150 cap) + £21.70 dealing = £546.70/year

£500,000 portfolio (£400k funds, £100k shares/ETFs, 6 trades a year):

• ii Plus: still £145.94/year — the flat fee does not move
• AJ Bell: £250,000 × 0.25% + £150,000 × 0.10% (next tier) + £100,000 shares capped at £42 + £16 dealing = £833.00/year
• Fidelity: £250,000 × 0.35% + £150,000 × 0.20% (next tier) + £100,000 shares capped at £90 + £15 dealing = £1,280.00/year
• HL: £400,000 × 0.35% = £1,400 + £100,000 × 0.35% capped at £150 + £21.70 dealing = £1,571.70/year

At £500,000, ii Plus saves £687/year against AJ Bell, £1,134 against Fidelity, and £1,426 against HL. Over 20 years, those savings — ignoring compounding — exceed £13,000, £22,000, and £28,000 respectively. Reinvested at a 5% real return, the compounded ii-versus-HL gap on a £500k portfolio approaches £50,000.

With 10-year gilts at 4.94%, the opportunity cost of the HL premium is stark: you could buy £1,426 of additional gilts every year, or fund a full S&S ISA contribution for a family member, just from the fee differential. The only structures that compete — iWeb's £100 one-off fee and Vanguard's 0.15% capped at £375 — either constrain investment choice or scale less aggressively than ii's flat structure.

ii is not universally cheapest. Four scenarios where it loses:

Small portfolios (under £20,000) holding mostly funds. £71.88 a year is a 0.36% drag on a £20,000 fund portfolio — higher than HL's 0.35%, Fidelity's 0.35%, and AJ Bell's 0.25%. For ISA holders building from £5,000-£15,000, Trading 212 (free) or InvestEngine (free for DIY ETF portfolios) are unbeatable on cost. Freetrade's Standard plan at £5.99/month matches ii Core's price but limits you to fractional shares with a wider FX spread.

Single-fund or robo-style investors. If you buy one global tracker and never switch, ii's flat fee overcharges you. Vanguard at 0.15% on a £30,000 LifeStrategy holding costs £45 a year — £27 cheaper than ii Core. Vanguard's 0.15% cap at £375 means it stays cheap up to £250,000 if you hold only Vanguard funds.

Active fund investors who value research depth. Fidelity charges 0.35% on funds — more than AJ Bell's 0.25% — but its Wealth Navigator tool, analyst coverage, and fund screening are widely considered best-in-class among UK retail platforms. Free fund trading sweetens the deal: an investor making 20 fund switches a year saves £79.80 at Fidelity vs ii Core. For active fund investors, the research premium may justify the custody cost. Our Fidelity ISA and SIPP fees breakdown has the full cost analysis.

Share-only frequent traders. Premium's £39.99/month with two free monthly trades works out to roughly £29.96/month for dealing + £2.99 per extra trade. A trader executing 30 share trades a month pays £29.96 + (28 × £2.99) = £113.68/month. On AJ Bell the same volume costs £42 cap + (30 × £3.50 frequent rate) = £147/month. ii Premium wins but only just — and most retail traders never hit 30 trades a month.

One final point on the Core ceiling. Cross £100,000 and you are bumped to Plus at £14.99/month automatically. Market fluctuations create billing risk: a strong month in equities flips you onto Plus, then a correction back below £100,000 keeps you there until you actively downgrade — with a minimum one-month lock on the new plan. Any investor circling £90,000-£110,000 should budget for Plus and treat Core as a temporary discount. For a deeper look at platform selection, our AJ Bell review and HL review break down each rival in detail.

Plus and Premium include free family accounts — a structural feature no UK competitor matches.

On Plus, you get five free family accounts, each with a Stocks & Shares ISA and Trading Account, capped at £100,000 per family member. They pay no monthly fee and trade at Core rates (£3.99 fund, £3.99 UK/US share). On Premium, family accounts are unlimited.

The maths for an investing family with two parents and two adult children: at HL, four ISAs at 0.35% on £50,000 each = £700/year in custody alone. At Fidelity: 4 × £175 = £700/year. At AJ Bell: 4 × £125 = £500/year. At ii Plus: £179.88/year total — every family account included.

For families targeting Junior ISA growth across multiple children, Plus's free Junior ISAs are worth roughly £36 a year per child (the cost of a JISA on AJ Bell at 0.25% × £20,000 typical balance = £50). HL has no JISA charges, but the ii family-bundle structure scales to the parents' accounts in a way HL's standalone JISA does not.

For most investing families, Plus's family feature alone justifies the £14.99/month over Core's £5.99, even before the portfolio hits £100,000. It is the most genuinely differentiated piece of ii's pricing — and the easiest to overlook in a headline fee comparison. See our investing hub for more on building a family investment strategy.

Headline plan fees miss two costs that hit international investors and dividend-focused portfolios hardest.

Foreign exchange: ii Core charges 0.75% on every conversion. A US-share-heavy investor buying $20,000 in dividend stocks and selling later pays 0.75% × $20,000 × 2 = $300 in FX over a single round trip. Plus drops this to 0.75% on the first £50,000 then 0.25%; Premium is a flat 0.25%. Compare with Trading 212's 0.15% spread or InvestEngine's free FX on most ETFs, and the gap matters for any active US trader. Fidelity charges 1.0% on FX up to £25,000 then 0.5% — meaning ii Plus beats Fidelity for any investor converting more than ~£10,000 to USD per year.

Dividend reinvestment: Core and Plus charge £0.99 per holding per dividend event. An investor with 20 dividend stocks paying quarterly = 80 events × £0.99 = £79.20/year on top of plan fees. Premium and HL both make dividend reinvestment free. Fidelity charges £1.50 per dividend reinvestment event — cheaper per-event but adds up fast for income portfolios. AJ Bell charges £1.50.

For a dividend-focused portfolio, this single cost can flip the comparison. A 30-stock UK income portfolio worth £80,000 at ii Core costs £71.88 + (120 × £0.99) = £190.68/year. The same portfolio at HL costs £80,000 × 0.35% = £280, but with the £150 share cap the actual custody is £150 + dealing = roughly £157/year plus free dividend reinvestment. HL's share cap inverts the comparison for share-only income portfolios above ~£40,000.

The broader point: ii's headline simplicity hides nuance. Run the numbers on your specific holdings rather than trusting the plan-tier comparison alone. Our ISA comparison tool covers cash ISAs — for S&S ISAs, the fee-comparison principle is the same: reach for a calculator before committing.

This article is for informational purposes only and does not constitute financial advice. You should seek independent financial advice from an FCA-authorised adviser before making any investment decisions. Investment platforms charge fees that may change without notice — always verify current pricing on each provider's official charges page before opening or transferring an account. Past performance and current cost comparisons are not a reliable indicator of future results. The value of investments can go down as well as up, and you may get back less than you originally invested.