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OneISA economics model — what the customer earns vs what the business makes

A representative customer, split across the wrappers. The left shows what they earn; the right shows what the platform makes from the same money — including the spread between what borrowers pay and what lenders receive. All figures illustrative.

The customer
What they earn
£0
net return, year one
Cash interest£0
S&S growth, net of fee£0
IFISA lending yield£0
After 10 years, reinvesting returns, their balance grows to £0.
The business
What OneISA makes
£0
revenue, year one · 0% of balance
Margin on cash buffer£0
Platform fee on S&S · kept competitive£0
IFISA lending spread£0
Instant-access financing · the use-based premium£0
Over 10 years , cumulative revenue is £0.
The IFISA spread — where peer lending pays the platform
Borrower pays
8.3%
customer needing liquidity
Lender earns
6.8%
customer who opted in
OneISA keeps
1.5%
the spread
The instant-withdrawal (liquidity) sleeve is near-riskless and ultra-short, so its slice of this spread is tiny — the meaningful spread income comes from the longer allowance-capture and external-lending sleeves. The platform never earns more than the borrower pays.
Where this sits against the market
DIY platforms
~0.15%
Vanguard · Dodl · InvestEngine
Simple / managed apps
0.45–0.75%
Moneybox · Plum · Nutmeg · Wealthify
OneISA blended
~0.6%
at parity, with more
The simplicity segment already prices above DIY. OneISA's blended take sits inside that band — not as the expensive outlier, but at parity while orchestrating more. The genuine premium is the instant-access financing line above: use-based, transparently priced, and impossible for competitors to match because they don't offer the feature.
Customer balance vs cumulative platform revenue
Customer balance Platform revenue (cumulative)

Illustrative model, not advice or a forecast. Returns assume reinvestment and no withdrawals; the customer's S&S return is a market assumption, not paid by the platform. The platform's “margin on cash” is the gap between what it earns placing the cash buffer and what it pays the customer — note this is the same mechanism that can incentivise keeping money in cash, which is why the alignment toggle exists. Spread income shown is a blended figure; in reality it varies sharply by sleeve. Defaults are plausible placeholders, not researched truth — change them in “rate assumptions”.