Custom Client Portal for an Accounting Firm in London: Cost and ROI

The verdict in three sentences

For a 30-person accounting firm in London still receiving 6,000 documents a month by e-mail, a custom client portal costs EUR 25,000 to 60,000 (about GBP 21,500 to 51,500) and is delivered in 3 to 4 months. Against SaaS licences at EUR 8-15 per client per month, custom becomes cost-effective from 300 to 400 active clients, especially if you want a fully branded experience. The real gain comes from the 2 hours saved per client per month on document collection and chasing.

The hidden cost of e-mail exchanges

In a 30-person firm serving 450 clients, staff spend a large share of their time searching inboxes for documents, renaming files, chasing clients and checking what is missing before year-end. That time is not billable and it degrades the client experience.

A well-designed client portal brings together:

• document upload by drag and drop or mobile photo, automatically filed by period and type;
• a list of expected documents per client, visible to them, with automatic reminders;
• electronic signature of engagement letters, accounts and board minutes;
• secure messaging attached to each client file, replacing e-mail threads;
• a client dashboard with tax, VAT and payroll deadlines;
• a Xero integration that pushes receipts and pulls bank reconciliation status.

Custom or SaaS: the figures side by side

SaaS remains sensible for a small firm with fewer than 150 clients or to test adoption. Beyond that, the cumulative gap becomes hard to justify.

What drives the custom budget

E-signature adds a per-envelope cost of roughly EUR 0.50 to 1.50 depending on volume and signature level. Plan UK or EU hosting compliant with UK GDPR, and two-factor authentication for financial data.

Mini case study

Isabelle, partner in a 30-person accounting firm in London, serves 450 active clients. Her team estimates losing 2 hours per client per month on collecting, chasing and sorting documents, or 900 hours a month across the production year.

She chooses a portal at EUR 48,000 (core, reminders, e-signature, Xero connector). Conservatively targeting an actual gain of 1 hour per client per month over 10 active months, the firm frees 4,500 hours a year. At a loaded hourly cost of EUR 45, that is EUR 202,500 of capacity redirected to billable advisory work or absorbed without hiring. Compared with a SaaS licence at EUR 10 per client, or EUR 54,000 a year, the custom portal pays back in under 12 months on licence savings alone. 2026 order of magnitude.

FAQ

How much does a client portal for an accounting firm cost?

A custom portal costs EUR 25,000 to 60,000 depending on modules, plus EUR 300 to 800 a month for hosting and maintenance. A SaaS licence costs EUR 8 to 15 per client per month.

How long does development take?

Three months for the core with reminders and e-signature, four months with a Xero connector and a mobile app.

Will clients actually use it?

Yes, if uploading is easier than e-mail. Firms that make the portal mandatory for document collection usually reach 70 to 85 % adoption within six months.

How secure is the financial data?

UK or EU hosting, encryption at rest and in transit, two-factor authentication, access logging and daily backups. An external security audit costs EUR 3,000 to 6,000.

Can we start small?

Yes, by first delivering document upload and reminders for EUR 25,000 to 32,000, then adding e-signature and messaging the following quarter.

Let's scope your project. Tell us your number of clients, your practice software and priority modules, and we will price a portal between EUR 25,000 and 60,000 delivered in 3 to 4 months. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.