How much practice management software costs an accounting firm in London in 2026

The verdict in three sentences

A custom practice management platform for an accounting firm in London costs between 40,000 and 90,000 EUR depending on scope (document management, client portal, deadline engine). Off-the-shelf suites (Xero Practice Manager, IRIS, CCH) run 40 to 90 EUR per user per month, a predictable subscription that scales with headcount. Custom becomes worthwhile beyond 15-20 staff or when your processes don't fit a generalist suite.

What a firm tool really covers

A firm doesn't just do bookkeeping: it manages an engagement portfolio, a tax and statutory deadline calendar, billing on fixed-fee or time basis, a compliant document store and a client portal for gathering paperwork. Software value is measured by how well it kills re-keying between these blocks.

A full project for a mid-sized firm takes 4 to 6 months, including acceptance testing and data migration.

Build vs licence: the 5-year math

The instinct is to compare the purchase price. The right lens is total cost of ownership (TCO) over five years, subscription and maintenance included. Here is a 2026 order of magnitude for a 20-user firm.

At 20 users the suite is cheaper over five years. Custom wins as headcount grows (the subscription tracks seats), when you bill non-standard work, or when you want to own the asset and fold it into your valuation.

Mini case study

Sophie, managing partner of a 24-strong firm in the City of London, pays 1,800 EUR a month in licences (75 EUR x 24). She's weighing a custom tool at 68,000 EUR bundling a client portal and deadline engine. Her firm loses about 6 hours per week per manager chasing missing documents. By automating intake through the portal she estimates recovering 3 hours/week x 24 people = 72 hours/week, roughly 3,100 hours/year. Valued at 35 EUR per production hour, that's 108,000 EUR of freed capacity a year. The investment pays back in under nine months, before licence savings.

FAQ

Do we have to drop Xero or IRIS to go custom?

Rarely entirely. Many firms keep the bookkeeping engine and build the pilot, portal and billing layer as custom software connected by API. Budget 5,000 to 12,000 EUR for those connectors.

How long to deploy?

Between 4 and 6 months for a full project, including 3-5 weeks of migrating existing engagements. A portal-and-deadlines MVP can ship in 10-12 weeks.

Does a client portal really save time?

Yes: automated document intake cuts chasing by 40-60% depending on the firm, and de-risks year-end. It's the module with the fastest immediate return.

What annual maintenance budget should we plan?

Expect 12-18% of the upfront investment per year, roughly 8,000 to 12,000 EUR for a 65,000 EUR project, regulatory updates included.

Should the software file VAT and returns automatically?

The deadline calendar can alert and pre-fill, but submission goes through your existing filing tools (HMRC MTD). Custom orchestrates; it doesn't replace the agent software.

Let's scope your project. Tell us your headcount, priority modules (portal, deadlines, billing) and an indicative budget, and we'll frame the most profitable scope. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.