ISA or pension? Where long-term money should go, and the Lifetime ISA's place
The same gross pay by two routes (pension with relief and a tax-free quarter, or ISA after tax and NI) compared on your rate now and in retirement, why the pension usually wins on tax and the ISA on access, and where the Lifetime ISA's 25% bonus fits.
One lever among many. Optimising your plan shows every lever, which ones apply to you and how they interact.
The pension-versus-ISA question is really a question about tax rates at two dates and about when you need the money. Put those three things in and the answer is usually clear; leave them out and the debate runs forever.
The arithmetic
Take £5,000 of gross pay. By salary sacrifice it all goes into a pension. As an ISA contribution it arrives after income tax and National Insurance: £2,900 for a higher-rate earner on £60,000, £3,600 for a basic-rate earner on £35,000. (From April 2029, sacrifice above £2,000 a year pays NI, which trims the pension's lead for larger amounts.) Both grow the same; on the way out a quarter of the pension is tax-free and the rest is taxed at the retirement rate, the ISA is tax-free entirely. At 5% growth over 20 years and a 20% retirement rate, the pension route ends with £11,277 against £7,695 in the ISA for the higher-rate earner, a 47% advantage, and £11,277 against £9,552 for the basic-rate earner, 18%. The ISA vs pension calculator runs your own rates; the pension tax relief calculator the relief on a personal contribution without sacrifice.
What the arithmetic leaves out
Access: pension money is locked until 55, 57 from April 2028, and an ISA is available tomorrow, which is why the emergency fund and any goal before 57 belong in an ISA whatever the tax says. Certainty: pension rules change and retirement tax rates are unknown; the ISA's tax-free status is the one that has been stable. Inheritance: from April 2027 unused pensions enter the estate, narrowing an advantage pensions used to have. And employer contributions, which are free money and only arrive through the pension.
The Lifetime ISA
For anyone under 40 the Lifetime ISA adds 25% to up to £4,000 a year (£1,000 of free money) usable for a first home under £450,000 or from age 60. From 28 to 50 at £4,000 a year and 5% growth it reaches about £329,000 at 60, £22,000 of it government bonus. The catch is the exit: withdrawing for anything else before 60 costs 25% of the withdrawal, which is 6.25% of your own money, so it suits a committed first-time buyer or a retirement saver who already fills the pension; the Lifetime ISA calculator shows both uses. For most people the order is: pension to the employer match, then ISA for anything before 57, then more pension for anything after.
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