How Much Does Custom Software Development Cost in the UK? A 2026 Pricing Guide

Ask five UK software agencies “how much will this cost?” and you will get five different numbers, usually with no explanation of what is driving the gap. That is not because anyone is being dishonest — it is because “custom software” covers everything from a three-week internal tool to a two-year regulated platform, and the cost drivers behind each are genuinely different. This guide breaks down what actually moves the number, so you can budget realistically before you ask anyone for a quote.

The short answer

• Simple internal tool or automation: £10,000 – £30,000
• MVP or first version of a product: £30,000 – £80,000
• Standard business application (customer portal, booking system, internal platform): £70,000 – £150,000
• Complex platform (multi-role, integrations, workflow engine): £150,000 – £350,000
• Enterprise system (regulated data, high availability, multiple integrations): £350,000+

Those bands hold across most UK agencies in 2026 because they mostly reflect the same thing: how many senior engineering months the work genuinely takes. What varies agency to agency is day rate, team structure, and — this is the part most quotes hide — what’s included after launch.

What actually drives the number

Two projects that sound similar on a call can cost very different amounts once you get into scope. The variables that matter most:

• Number of user roles. An app with one user type (just “the customer”) is a fraction of the cost of one with customer, staff, and admin roles each needing different permissions and views.
• Integrations. Every third-party system you connect to — payments, CRM, accounting, a legacy database, a supplier API — adds discovery time, error handling, and testing that rarely shows up in an initial estimate.
• Data migration. If you are replacing something, moving existing data across cleanly is often underestimated by 2-3x versus building the new system itself.
• Compliance requirements. GDPR is the baseline for everyone; FCA, NHS DSPT, or PCI-DSS requirements add audit trails, access controls and documentation that take real engineering time, not just a checkbox.
• Design maturity. A pixel-perfect, fully bespoke interface takes longer than a clean interface built on a proven component system — neither is wrong, but they cost differently.

UK day rates by seniority (2026)

If you are comparing quotes, it helps to know roughly what a day of engineering time actually costs in the UK market right now:

• Junior engineer: £250 – £400/day
• Mid-level engineer: £400 – £600/day
• Senior engineer: £550 – £850/day
• Principal / architect: £800 – £1,200+/day
• Central London agency premium: often 15-30% above the same seniority remote or regional

A quote built entirely from junior day rates looks cheap on paper but usually means more senior review time later, more rework, and a longer path to something production-ready. A quote built entirely from senior rates is accurate but expensive for work that does not need that level of seniority. The agencies worth hiring blend the two deliberately — senior engineers on architecture and the hard 20%, less senior time on the more mechanical 80%.

The costs most quotes leave out

• VAT. UK agency quotes are almost always ex-VAT. Add 20% before you compare to a number that already includes it.
• Hosting and infrastructure. Cloud hosting for a mid-size platform typically runs £150-£800/month depending on traffic and redundancy — separate from the build cost, and it starts on day one of going live, not after.
• Third-party service costs. Payment processing fees, email/SMS providers, mapping APIs, monitoring tools — usually small individually, £100-£500/month combined for a typical business application.
• Ongoing maintenance and support. Security patching, dependency updates and bug fixes after launch. Budget 15-20% of the build cost per year if you want the system actively maintained rather than left to rot.
• IR35 exposure. If your quote comes from an individual contractor rather than an agency, your business may carry off-payroll working (IR35) determination responsibility — a real administrative and financial risk we cover in detail in a separate article.

Fixed price vs time and materials

Both models are common in the UK market and both are legitimate — the mismatch happens when the wrong one gets used for the wrong kind of project.

• Fixed price works well when scope is genuinely well understood upfront — a known integration, a defined feature set, a tightly-specified internal tool. You get budget certainty; the agency prices in a risk buffer to cover the unknowns, which is why fixed-price quotes usually run 10-25% higher than an equivalent T&M estimate.
• Time and materials (T&M) works better for anything where the full picture only becomes clear once you start — most genuinely new products fall into this category. You pay for actual work done, scope can flex as you learn, but budget certainty is lower unless the engagement is capped or reviewed in short cycles.
• Capped T&M — a not-to-exceed ceiling with weekly or sprint-based reporting — is usually the sensible middle ground for most first-time software buyers: real cost transparency, but a number you can plan against.

A worked example

Take a mid-size business platform: a customer-facing booking system with an admin dashboard, payment integration, and a data migration from an existing spreadsheet-based process. Realistically:

• Discovery and technical design: 2-3 weeks, £8,000-£15,000
• Core build (booking flow, admin dashboard, payments): 10-14 weeks, £70,000-£110,000
• Data migration and integration testing: 2-3 weeks, £10,000-£20,000
• QA, UAT and launch: 1-2 weeks, £5,000-£10,000
• Total: roughly £95,000-£155,000 over a 4-6 month timeline, plus ongoing hosting and a maintenance retainer once live.

The gap between the low and high end of that range is almost entirely down to how much of the scope was locked down before the quote was written — which is the single biggest lever you have to control cost.

How we price at Autratech

We run a capped-scope engineering retainer rather than per-project fixed bids, because it removes the incentive to under-scope a quote to win the work and then renegotiate mid-project — a pattern that is unfortunately common in this market. You get a named senior team, a transparent monthly rate, and the ability to scale the engagement up or down as the roadmap changes, without a new contract negotiation every time priorities shift. Full detail is on our pricing page.

How to get an accurate quote, not just a fast one

The single biggest lever you control is how well-defined the scope is before anyone prices it. A discovery phase — even a short, paid one — almost always pays for itself by turning a rough estimate into an accurate one. Before you request quotes, it is worth arriving with:

• A written list of the user roles the system needs and what each one can see and do.
• Every existing system it needs to talk to, even the ones that feel too minor to mention.
• Whether there is data to migrate, and roughly how much, and how clean it currently is.
• Any compliance requirement that applies to your sector, stated explicitly rather than assumed to be obvious.
• A rough sense of your own deadline pressure — a genuinely fixed date changes the pricing conversation.

Agencies that ask detailed questions before quoting are, more often than not, the ones who will not need a change order three months in. Agencies that quote a number after a 20-minute call are pricing risk into the number somewhere — you just cannot see where yet.

Feature-level cost examples

Cost bands by project type are a useful starting point, but individual features are where budgets actually get built. Rough UK ranges for common building blocks, on top of a core application:

• User authentication with roles and permissions: £4,000 – £12,000, more with SSO or complex permission hierarchies.
• Payment integration (Stripe or similar, single currency): £3,000 – £8,000; multi-currency or marketplace payment splitting adds significantly more.
• Admin dashboard with reporting: £8,000 – £25,000 depending on how much of the business logic it needs to expose.
• Third-party API integration (CRM, accounting, logistics): £3,000 – £15,000 per integration, heavily dependent on how well-documented the third-party API actually is.
• Data migration from a legacy system: £5,000 – £30,000+, driven almost entirely by how clean and well-structured the source data is.

These add on top of the base project bands above rather than replacing them — a “standard business application” quote should already assume authentication is included, for example, but a marketplace payment split or a fragile legacy data migration is exactly the kind of thing worth pricing separately and explicitly.

Frequently asked questions

Is it cheaper to hire developers directly than to use an agency?

For a single, long-running product with stable headcount, an in-house hire is usually cheaper per month over several years. For anything shorter-term, or needing more than one discipline, the recruitment cost, management overhead and continuity risk of direct hiring usually make an agency the more cost-effective choice once you account for total delivered output, not just salary versus day rate.

Why do quotes for the same brief vary so much between agencies?

Usually one of three reasons: different assumptions about scope that were never made explicit, a different seniority mix behind the number, or one agency pricing in more risk buffer than another because they asked more questions upfront and uncovered more unknowns. Ask each agency to break their number down by phase — it usually reveals which one is which.

Should I get a fixed price before starting?

Only if the scope is genuinely well understood already. A fixed price on a poorly-defined scope just moves the risk of change into a change-order process later, which is often more expensive and more adversarial than a capped time-and-materials arrangement would have been from the start.

How much should I budget for ongoing costs after launch?

As a rule of thumb, 15-20% of the original build cost per year covers active maintenance, security patching and small improvements. Hosting and third-party service costs sit on top of that and scale with usage rather than build size.

If you have a rough idea of what you want to build and want an honest number rather than a sales-optimised one, we are happy to look at it with you.