Lightyear’s multi-currency wallets sit on the GIA in the UK and on the Personal Account in the EU, never inside the ISA — inside a Lightyear Stocks and Shares ISA, every trade pays the standard 0.10% FX with no wallet workaround. Trading 212’s ISA is the same story: its Multi-Currency Account only works on Invest, so the ISA is single-currency there too. Neither broker’s ISA offers a way around FX that its standard account does.

On rates: Lightyear’s UK Cash ISA pays interest that tracks the Bank of England base rate. The rate is variable, so check the current figure in the app before opening. Trading 212 also runs a Cash ISA, but the rate it publishes applies to new clients only — if you already hold an account, your actual rate shows inside the app — so there’s no comparable number to quote here.

Lightyear holds EUR, GBP and USD as separate wallets. Fund the matching wallet by bank transfer and buy an asset priced in that currency, and you pay no FX fee at all — on the GIA in the UK and the Personal Account in the EU, never inside the ISA. Trading 212’s Multi-Currency Account spans twelve currencies on Invest: on each order you choose either your Primary Currency or the Instrument Currency, and picking the Instrument Currency avoids the FX fee too. Your Primary Currency is fixed at signup and can’t be changed, and there’s no automatic conversion — an order can go partly or wholly unfilled if the selected currency’s balance is too low. Pies hold cash in your Primary Currency, and any conversion inside a Pie, including dividend reinvestment, is still charged at 0.15%.

Lightyear’s cash interest and its Vaults/Savings product are two different things, and mixing them up is the most common error in broker comparisons. Cash interest is a straightforward rate on money sitting uninvested: 1.00% APY on GBP for UK residents, 0.00% on USD, and — easy to miss — no EUR row at all. Rates are variable and accurate as of 05-August-2026. Uninvested EUR cash earns nothing on Lightyear, in every country.

Vaults (UK) and Savings (EU) are a separate product: an investment in money market funds, where capital is at risk rather than held as a deposit. Lightyear charges its own 0.10% annual fee on EUR and GBP funds and 0.15% on USD, on top of the fund manager’s own fee, and it isn’t available in Belgium. These holdings sit outside FSCS protection.

Trading 212 pays interest on Invest, Stocks ISA, Cash ISA, SIPP and CFD balances, but it’s opt-in — skip it and Trading 212 keeps the interest itself. The rate depends on which entity you’re with and is quoted in three non-comparable notations (AER in the UK, p.a. in the EU, APY in Cyprus); only new-client rates are published, so your actual rate lives inside the app. Where that cash sits in money market funds it isn’t deposit-guaranteed — Trading 212 isn’t a bank.

Both brokers execute meaningful volume off-exchange — the shapes just differ. Lightyear routes UK-listed instruments, including LSE-listed UCITS ETFs, through Infront, a Retail Service Provider hub where competing market makers quote firm prices and the best one is taken. That’s a competitive-quote process rather than a single dealer, which is the cleaner version of this model, but it’s still bilateral and off-exchange rather than on the LSE order book. Separately, when Lightyear splits a share into fractions, that fractional portion trades against Lightyear Europe AS’s own book rather than any venue — in the UK, Lightyear UK acts as your agent while the counterparty is its own sister company.

Trading 212 passes EU orders to its Irish affiliate, which executes them either on a trading venue or on its own systematic internaliser, at a price no worse than the reference exchange, and takes no payment for routing orders internally. Trading 212’s own disclosures note that routing to a group entity creates a potential conflict of interest, and that off-venue execution carries more counterparty and settlement risk than trading on an exchange.

Neither uses payment for order flow — effectively banned in the UK since 2012, and an absolute EU-wide ban since 30 June 2026. For someone buying a UCITS ETF monthly, the practical difference is small; the structural difference is real, and both firms disclose it themselves. For very large single orders, where execution quality matters more, Interactive Brokers is worth the extra complexity over either platform.

On headline cost, Trading 212 keeps the edge for EU investors: 0.15% FX against Lightyear’s 0.35%. Lightyear’s counterweights are narrower than they look — it never lends out client shares or cash on any account, but Trading 212’s EU entity can’t opt into securities lending either, so that point is a wash for EU clients specifically. What does shift the calculation: Lightyear also accepts Belgian residents, where Trading 212 doesn’t operate, and both brokers can get you to 0% FX on EUR-priced UCITS ETFs — Lightyear if you fund a EUR wallet by SEPA transfer, Trading 212 by selecting the Instrument Currency on the order. Where you’ll actually pay is on EUR-to-USD conversions for anything priced outside the euro; there, Trading 212’s 0.15% stays the cheaper option.

For UK investors, Lightyear’s personal-tier schedule is the cheapest on this page: 0.10% FX plus free execution on UK, US and EU stocks inside both the ISA and GIA. That headline comes with real trade-offs. The multi-currency wallet that lets you dodge FX entirely only works on the GIA — inside the ISA you’re paying that 0.10% on every conversion regardless. UK-listed instruments, including LSE UCITS ETFs, are executed off-exchange through a market-maker hub rather than on the exchange order book. And uninvested GBP cash earns 1.00% APY, variable and accurate as of 05-August-2026 — a real number, but not a competitive one against the Cash ISA, which tracks the Bank of England base rate and is where Lightyear’s strength sits for UK savers holding cash inside the wrapper.