The verdict in three sentences
A custom client portal for a Paris accounting firm ranges from 15,000 to 45,000 EUR excl. VAT in 2026, with a 3 to 5 month timeline. The concrete gains are measurable within the first quarter: 30% fewer inbound emails and roughly 5 hours saved per week per staff member thanks to integrated DMS and e-signature. The financial break-even typically lands around 18 to 24 months for a firm of 8 to 15 staff.
What an accounting client portal covers in 2026
A portal is not a mere file drop. For a firm, it centralizes document exchange, filing validation and the client relationship. The modules below represent the most requested items in 2026.
| Module | Cost range (EUR excl. VAT) | Indicative timeline |
|---|---|---|
| Portal core + authentication | 5,000 - 9,000 | 4-6 weeks |
| DMS with automatic filing | 4,000 - 8,000 | 3-5 weeks |
| E-signature (eIDAS) | 3,000 - 6,000 | 2-4 weeks |
| SSO / Google & Microsoft login | 2,000 - 4,000 | 2-3 weeks |
| Secure messaging + notifications | 2,500 - 5,000 | 2-4 weeks |
| Client dashboard (deadlines, VAT) | 3,500 - 7,000 | 3-5 weeks |
| Accounting software integration (API) | 4,000 - 10,000 | 4-6 weeks |
A Starter project (core + DMS + signature) runs around 15,000-20,000 EUR excl. VAT. A full project with production-software integration and SSO climbs toward 35,000-45,000 EUR excl. VAT.
Quantified productivity gains
The real buying argument is not comfort, it is billable time recovered. Here are the orders of magnitude observed in 2026 on comparable firms.
| Indicator | Before portal | After portal | Change |
|---|---|---|---|
| Client emails / week / staff | 120 | 84 | -30% |
| Document collection time (per file) | 45 min | 18 min | -60% |
| Manual reminders / month | 90 | 30 | -67% |
| Average document signing delay | 4 days | 6 hours | -95% |
| Admin hours / week / staff | 8 h | 3 h | -5 h |
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Mini case study
Sophie, partner at a 12-person accounting firm in the 9th arrondissement of Paris, invests 28,000 EUR excl. VAT in a portal (core + DMS + signature + SSO). Each staff member saves 5 hours per week, i.e. 60 weekly hours for the team. At a 45 EUR loaded hourly cost, that is 2,700 EUR per week, roughly 118,000 EUR per year of freed capacity. Even converting only a quarter of that time into extra billing, the portal pays for itself in under 12 months.
FAQ
How long to deploy an accounting portal? Expect 3 to 5 months from scoping to production, depending on the number of integrations. A core without production-software connection can ship in 10 to 12 weeks.
Is e-signature truly compliant? Yes, with an eIDAS provider (advanced or qualified level) the signature carries the same legal value as a handwritten one. The extra cost per signature is around 0.50 to 2 EUR depending on volume.
Can the portal connect to our accounting software? Most market solutions expose an API. Integration costs 4,000 to 10,000 EUR excl. VAT and eliminates double entry, the main source of errors.
What annual maintenance budget should we plan? In 2026, expect 15 to 20% of the initial cost per year, i.e. 3,000 to 8,000 EUR excl. VAT, covering secure hosting, updates and support.
Is it worth it for a small 5-person firm? Yes, with a reduced scope of 15,000-18,000 EUR excl. VAT. The 5 h/week gain per staff stays proportionally identical and the return lands in 18 to 24 months.
Let's scope your project. Tell us your headcount, your production software and priority modules (DMS, signature, SSO) for a precise estimate between 15,000 and 45,000 EUR excl. VAT. 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.
