The verdict in three sentences
Custom practice management software for an accounting firm costs between 40,000 and 110,000 EUR in 2026, while a vertical SaaS runs at 30-80 EUR per staff member per month with no ownership. Custom becomes worthwhile above 12-15 staff or when integration with production tools and a branded client portal turn strategic. Below that, a well-configured SaaS remains the rational choice, provided you accept vendor lock-in.
Custom vs SaaS: the 2026 numbers
The decision is not only about entry price. Look at code ownership, integration capacity and recurring cost over time.
| Criterion | Vertical SaaS | Custom |
|---|---|---|
| Upfront cost | 0-3,000 EUR (setup) | 40,000-110,000 EUR |
| Recurring cost | 30-80 EUR/staff/month | Hosting 80-300 EUR/month |
| Code ownership | No | Yes |
| Production integration | Limited, standard | Full, tailored |
| Branded client portal | Rare | Yes |
| Time to deploy | 2-6 weeks | 3-6 months |
| Enhancements | Vendor roadmap | On demand |
For a 20-person firm, a SaaS at 55 EUR/month is 13,200 EUR/year, or 66,000 EUR over five years without ever owning the tool.
What makes up a custom build budget
Price mostly depends on scope. Here is a realistic breakdown (2026 order of magnitude, 15-25 staff).
| Module | Range (EUR) | Timeline |
|---|---|---|
| Client file management | 8,000-18,000 | 3-5 wks |
| Tax deadline tracking | 6,000-14,000 | 2-4 wks |
| Document management (DMS) | 7,000-16,000 | 3-5 wks |
| Client portal + upload | 9,000-22,000 | 4-6 wks |
| Production integration | 8,000-20,000 | 3-6 wks |
| GDPR + security | 4,000-10,000 | 2-3 wks |
| Training + data migration | 3,000-8,000 | 2-3 wks |
GDPR compliance is not optional: processing register, encryption at rest, access logging and EU hosting are expected by your clients and regulators.
Mini case study
Sophie runs a 22-person accounting firm in central London. She currently pays 55 EUR/staff/month in SaaS, i.e. 14,520 EUR/year. She invests 74,000 EUR in a custom tool with a client portal and production connector, plus 2,400 EUR/year hosting.
Over five years, the SaaS would cost 72,600 EUR; custom comes to 74,000 + 12,000 = 86,000 EUR, but she saves 6 hours/week of document collection (automatic portal), about 280 hours/year valued at 45 EUR, so 12,600 EUR/year. Custom pays back by the end of year 2 and becomes a firm asset.
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FAQ
What is the minimum price for custom accounting firm software in 2026?
Expect a floor of 40,000 EUR for a credible core (files, deadlines, basic DMS). Below that you get a prototype, not a reliable production tool.
Is SaaS cheaper than a custom build?
Short term yes, but a 20-person firm spends roughly 66,000 EUR over five years on SaaS owning nothing. Above 15 staff, custom makes economic sense.
Can a custom tool integrate production software?
Yes, via API or file bridges. Budget 8,000 to 20,000 EUR for a robust, tested integration.
How long does a custom project take?
Between 3 and 6 months depending on scope, delivered in batches to avoid the tunnel effect and train teams gradually.
How do you guarantee GDPR compliance?
EU hosting, encryption, access logging, processing register and processor clauses. Dedicated budget: 4,000 to 10,000 EUR.
Let's scope your project. Tell us your headcount, current production tools and whether the client portal is a priority. 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.
