How Much Does Custom Software Cost in the UK?

Custom software in the UK runs from a few thousand pounds for a simple tool to well into six figures for something complex. The number tracks scope first and who builds it second. Two things specific to the UK, contractor rules and the true cost of a hire, shift the maths more than most people expect.

The ranges below are typical UK market figures in pounds, not our quotes. Anyone naming a firm price before hearing the scope is guessing.

Rough UK ranges

• £10k–£30k: a focused tool or MVP with one core job.
• £30k–£75k: a real product with payments and a couple of user types.
• £75k and up: multiple integrations, regulated data, or heavier complexity.

UK day rates, and what they hide

A UK freelance developer might sit around £350 to £600 a day, a specialist agency higher. A cheaper day rate isn't a cheaper project if it buys more management, rework or a longer timeline. Judge the total cost to a working result, not the headline rate.

Contractors and IR35

Since the off-payroll rules changed, UK businesses carry responsibility for whether a contractor sits inside or outside IR35, and getting it wrong brings tax risk. It's one reason many teams prefer a fixed-scope engagement with a studio or agency over a string of day-rate contractors: the deliverable and the responsibility are cleaner.

The real cost of building in-house

A permanent developer isn't only their salary. Add employer National Insurance, pension, equipment, recruitment and the months to hire and onboard. For a single project, that fully loaded cost often beats the price of paying a team to deliver it and move on. In-house earns its place when the work is continuous, not one-off.

How to keep the number down

The same levers apply wherever you build. Cut to one core loop, retire the biggest risk with a proof of concept before you commit, and check you're pricing an MVP rather than the finished product. Before you build at all, run the build vs buy question, since the cheapest custom software is the custom software you didn't need to write.

In short

Budget by scope, factor in IR35 and the loaded cost of a hire, and default to buying the commodity parts. We're a UK-rooted studio working with clients here and worldwide, so if you want a grounded estimate, send us the outline.