The verdict in three sentences
A bespoke client portal for a London accounting firm costs between GBP 16,000 and GBP 40,000 in 2026, delivered in 10 to 16 weeks. SaaS suites such as Xero, FreeAgent or Dext bundle a client area from GBP 12-35 per user per month but lock you into their UX and roadmap. Custom is worth it once you manage 150+ clients or the portal becomes a genuine commercial differentiator.
What a bespoke client portal costs in 2026
Pricing tracks scope: a simple document drop versus a real DMS with approval workflow and e-signature. Below are London ranges seen in 2026.
| Scope | Features | Cost GBP | Timeline |
|---|---|---|---|
| Essential | Document upload, notifications, history | 16,000 - 21,000 | 10-12 wks |
| Standard | + DMS, e-signature, SSO | 23,000 - 30,000 | 12-14 wks |
| Advanced | + approval workflow, ledger API, dashboard | 32,000 - 40,000 | 14-16 wks |
| Complex bespoke | + billing, chasers, multi-office | 40,000+ | 16-20 wks |
Add UK/EU GDPR-compliant hosting (around GBP 70/month for a secure shared foundation) and support and maintenance (15%/year of build cost, i.e. GBP 2,400-6,000/year).
Bespoke or SaaS module: the real maths
Suites like Xero and FreeAgent already ship a client area. The decision rests on 3-year total cost and how much personalisation you need.
| Criterion | Bespoke portal | SaaS module (Xero / FreeAgent) |
|---|---|---|
| Upfront cost | GBP 16,000 - 40,000 | 0 (in subscription) |
| Recurring cost | GBP 70/mo hosting + support | GBP 12 - 35/user/mo |
| 3-year cost (10 users) | ~GBP 25,000 - 54,000 | GBP 4,320 - 12,600 |
| UX personalisation | Full, firm-branded | Limited to vendor theme |
| Data portability | You own the database | Vendor dependency |
| E-signature | Integrable (eIDAS/UK) | Plan-dependent |
SaaS is cheaper on gross cost. Bespoke wins when brand, premium client experience and independence from the vendor drive your retention strategy.
Mini case study
Mark, a partner at a 240-client firm in the City, lost 6 hours a week chasing missing documents by email. A Standard portal at GBP 27,000 with secure upload, automated chasers and e-signature cut chasing by 70%. Estimated saving: 4 hrs/week over 46 weeks, ~184 hrs/year at GBP 50/hr = GBP 9,200/year. Payback in just under 3 years, before brand and retention value.
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FAQ
Is a bespoke portal GDPR-compliant and confidential enough?
Yes, with UK/EU hosting, encryption at rest and in transit, and access logging. Compliance work is baked into the build (roughly 8-12% of budget).
Can the portal connect to my accounting software?
Usually yes, via API (Xero, Sage, QuickBooks). A connector is GBP 2,500-7,000 depending on the vendor's openness.
Is the e-signature legally binding?
An advanced or qualified eIDAS/UK signature has full evidential weight. The third-party service costs roughly GBP 0.40-1.60 per signature by volume.
How long until go-live?
Allow 10-16 weeks for a Standard portal, including 2-3 weeks of testing and data migration.
What annual maintenance should I budget?
Support at 15%/year of build cost covers fixes, security updates and small enhancements, i.e. GBP 2,400-6,000/year.
Let's scope your project. Tell us your client volume, accounting stack and e-signature needs and we will define scope and an indicative budget of GBP 16,000-40,000. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
