The verdict in three sentences
For an accounting firm with 450 clients in London, a SaaS client portal remains the right choice as long as the firm accepts its functional limits and a cost that grows with every client. A custom portal at EUR 22,000 to 38,000 excl. VAT becomes more profitable around 26 months against an entry-level SaaS, and much sooner against a premium plan. The decision comes down to three criteria: the quality of the API connector to the practice software, data residency in the UK or EU, and planned portfolio growth.
SaaS or custom: the numbers
The partner who wants to centralise document collection and engagement letter signing usually compares a ready-made subscription with a 3 to 4-month project. Both options solve the basic problem: no more documents sent by email, automatic reminders, e-signature. The difference lies in long-term cost and integration with the production workflow.
| Criterion | Market SaaS | Custom portal |
|---|---|---|
| Initial cost | EUR 0 to 2,000 (setup) | EUR 22,000 to 38,000 |
| Recurring cost (450 clients) | EUR 1,800 to 4,050 per month | EUR 500 to 800 per month (hosting, maintenance) |
| 3-year cumulative cost | EUR 64,800 to 147,800 | EUR 40,000 to 66,800 |
| Time to launch | 2 to 4 weeks | 12 to 16 weeks |
| Practice software connector | Standard, sometimes partial | Dedicated API, custom fields |
| Workflow customisation | Limited | Full (per engagement, per client) |
| Hosting | Vendor's choice | UK or EU, chosen by the firm |
SaaS has a clear advantage: it is live within a month. Custom takes the lead once the firm passes 300 to 400 clients or wants a client journey specific to its organisation (collection by VAT quarter, graduated reminders, dashboard per staff member).
What a EUR 22,000 to 38,000 custom portal includes
| Module | Base version | Full version |
|---|---|---|
| Client area and document upload | EUR 6,000 | EUR 8,500 |
| Automatic deadline reminders | EUR 2,500 | EUR 4,500 |
| E-signature of engagement letters | EUR 3,000 | EUR 5,000 |
| API connector to practice software | EUR 5,500 | EUR 9,000 |
| Staff dashboard | EUR 2,500 | EUR 5,000 |
| Security, audit logs, GDPR compliance | EUR 2,500 | EUR 6,000 |
| Total excl. VAT | EUR 22,000 | EUR 38,000 |
On hosting, one point deserves clarification: health-data certified hosting is not required for an accounting firm unless it handles medical data. However, UK or EU hosting is in practice mandatory to comply with UK GDPR and professional confidentiality rules. A server in London or Frankfurt with encryption at rest and daily backups costs EUR 150 to 300 a month.
Time saved, an often underestimated argument
Whether the firm picks SaaS or custom, the operational gain is similar: about 6 hours per staff member per month recovered on reminders, sorting documents and tracking signatures. Custom adds an extra gain when the API connector pushes classified documents straight into the practice software, avoiding 1 to 2 hours of re-keying per staff member per month.
| Task | Before portal | With portal |
|---|---|---|
| Chasing missing documents | 3 h per month | 0.5 h per month |
| Sorting and filing documents | 2.5 h per month | 0.5 h per month |
| Tracking engagement letters | 1.5 h per month | 0 h |
| Total per staff member | 7 h | 1 h |
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
Emma, partner at a London accounting firm with 450 clients and 8 staff, compares a SaaS at EUR 4 per client (EUR 1,800 a month) with a custom portal at EUR 30,000, plus EUR 650 a month for hosting and maintenance. The custom option saves EUR 1,150 a month, a break-even point of about 26 months. Either way, her 8 staff save 6 hours a month each, 48 hours in total, about 30% of a full-time role. If the firm grows to 600 clients by 2028, the SaaS rises to EUR 2,400 a month and the custom break-even drops below 18 months.
FAQ
Is a custom client portal profitable for a 450-client firm?
Yes in the medium term: against a SaaS at EUR 4 per client, break-even is around 26 months. Against a EUR 9 per client plan, it falls below 12 months.
Do we need specialised certified hosting?
No, health-data certifications only apply to medical data. Encrypted, backed-up hosting in the UK or EU is enough and costs EUR 150 to 300 a month.
Can the portal connect to our practice software?
Yes, through the vendor's API where available, which accounts for EUR 5,500 to 9,000 of the budget. Documents arrive filed by client and financial year, with no re-keying.
How long does a custom portal take to launch?
Allow 12 to 16 weeks, including 3 weeks of testing with a pilot group of 20 to 30 clients before opening it to the whole portfolio.
Are e-signed engagement letters legally valid?
Yes, an advanced electronic signature compliant with UK eIDAS rules is legally binding. Usage costs run around EUR 1 to 2 per signature depending on the provider.
Let's scope your project. Tell us your client count, practice software and collection workflows, and we will price the portal, the API connector and the break-even against your current SaaS. 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.
