Pension administration rarely makes headlines, yet it sits underneath a large share of UK retirement saving. Two London-listed companies approach it from opposite ends: PensionBee (LSE:PBEE) runs a direct-to-consumer online pension for hundreds of thousands of savers, while InvestAcc Group (LSE:INAC) administers specialist self-invested pensions for a far smaller, typically wealthier client base.

They are worth understanding together because both have published fresh half-year numbers within the past six weeks, and those numbers describe two very different economic models. PensionBee is scaling quickly but was still loss-making on an adjusted EBITDA basis in the first half of 2026; InvestAcc is smaller by Revenue but already profitable, helped by an Acquisition and by treasury income.

This is an explainer built on the latest reported results, not a reaction to a single day's share-price move.

What pension administration actually involves

Pension administration covers the record-keeping, transfers, contributions, Investment dealing, tax-relief claims and benefit payments that sit behind every pension. Providers are paid through asset-linked fees, fixed per-scheme charges, or both.

Two wrappers matter here. A SIPP (self-invested personal pension) lets savers choose from a wide range of investments. A SSAS (small self-administered scheme) is an occupational scheme usually set up by company directors, which can hold Assets such as commercial property. Both require specialist administration and are regulated activities.

Because much of the cost base is broadly fixed, both companies emphasise growth in assets under administration (AUA), the value of client assets they administer.

PensionBee: rapid growth, with profitability still the target

PensionBee's half-year report for the six months to 30 June 2026 showed AUA of £8.6bn, up 37% from £6.3bn a year earlier, and 327,000 invested customers, up 14% from 286,000. Net flows, meaning new money in minus money out, were £493m against £423m in the first half of 2025.

Revenue rose 40% to £26.4m (H1 2025: £18.9m), and the company reported annualised run-rate revenue of £55.8m. Its revenue margin, which expresses fees as a share of AUA, was 0.68%, compared with 0.63% a year earlier.

Profitability remains a work in progress. Adjusted EBITDA (earnings before interest, tax, Depreciation and amortisation, excluding items management treats as non-recurring) was a loss of £1.1m, narrower than the £2.9m loss a year before. The loss before tax was £2.9m (H1 2025: £5.1m loss).

A statutory profit after tax of £8.2m was flattered by an £11.2m deferred tax asset, an accounting entry rather than cash earned.

Part of the drag is the US expansion. The same report shows US AUA of £4m and a US adjusted EBITDA loss of £2.6m for the half. Group cash stood at £31m, down from £34m a year earlier.

Management's stated objectives, which assume market stability, are group revenue of £100m or more with a c.20% adjusted EBITDA Margin by year-end 2029, rising to £250m or more and a c.50% margin by 2034. These are targets, not forecasts. PensionBee has announced that results for the quarter to 30 September 2026 will be published on 21 October 2026.

InvestAcc: an acquisition-led specialist

InvestAcc Group is the former Marwyn Acquisition Company II, a cash shell that completed the InvestAcc acquisition and was re-admitted to the transition share category of the Official List and to trading on the Main Market on 9 October 2024, adopting the INAC ticker. That announcement confirms the company is incorporated in the British Virgin Islands.

Its interim results for the six months to 30 June 2026, published on 24 September, showed revenue of £13.8m, up from £6.0m. Pension administration contributed £6.9m, financial advice £1.4m, appointed-representative services £0.6m and treasury £5.0m.

Group EBITDA was £4.9m (H1 2025: £1.3m), while trading EBITDA, a measure before central costs, was £6.8m, a 48.9% margin. Operating profit was £2.1m and profit after tax £1.5m, against losses a year earlier. Pension scheme AUA reached £10.6bn (H1 2025: £5.8bn) across 19,251 schemes.

Much of that step-up came from buying AJ Bell's Platinum SIPP and SSAS book. InvestAcc's results for 2025 put the consideration at up to £25.0m, with completion on 3 November 2025 adding 3,412 schemes and £3.3bn of AUA. The same results showed net Debt of £12.7m, about 3.0 times group EBITDA, at the end of 2025.

According to the interim announcement, management targets further acquisitions at 5 to 8 times EBITDA and reports multiple ongoing discussions across specialist providers, life companies and platforms.

Comparing the two models

On our reading, the figures highlight a basic difference in customer economics. Annualising the half-year figures crudely, PensionBee earns roughly £160 of revenue per invested customer, while InvestAcc earns more than £1,400 per scheme. Specialist SIPP and SSAS clients are far fewer, but each carries larger balances and more complex administration.

The quality of revenue also differs. PensionBee's income is mainly asset-based fees, so it moves with markets. InvestAcc's £5.0m treasury line is more than a third of group revenue. Across the SIPP industry, treasury income commonly reflects interest earned on client cash, which would make it sensitive to Bank of England rate decisions, although readers should check the company's own definition.

Growth sources diverge too. PensionBee's AUA growth comes from consolidating savers' old pensions plus market gains. InvestAcc reports 14% organic scheme growth, with Platinum adding about 3,300 schemes; acquisitions bring scale but also integration work and debt.

Risks and dates to monitor

For PensionBee, the key questions are whether cost discipline turns adjusted EBITDA sustainably positive, how much the US Business continues to absorb, and whether net flows hold up. UK cost per invested customer rose to £263 from £251. The Q3 update on 21 October 2026 is the next scheduled data point.

For InvestAcc, the watch-points include the durability of treasury income if interest rates fall, integration of Platinum, Leverage from any further acquisitions, and service levels. Its reported service-quality measure slipped to 92.7% from 97.3%, and 12-month client retention eased to 94.7% from 96.3%. The company also highlights a Financial Conduct Authority consultation on how pension scheme money and assets are held, with compliance expected by 2029–30.

The bottom line

PensionBee (LSE:PBEE) and InvestAcc (LSE:INAC) make pension administration worth understanding because they show two distinct routes to scale: building a mass-market Brand organically while working towards profitability, or assembling an already profitable specialist platform through acquisitions.

Neither route is risk-free. PensionBee must show progress towards its margin targets; InvestAcc must show that growth and treasury income hold up through integration and any fall in rates.