The verdict in three sentences
In 2026, an accounting firm chooses between a vendor subscription of 40 to 90 EUR per staff member per month and a custom platform of 35,000 to 80,000 EUR one-shot. Custom becomes profitable from around 15 staff over a 3-year horizon, especially if your engagement workflows are unusual. Below that, the subscription stays the pragmatic choice — unless you strongly need data ownership and a branded client portal.
What a firm management tool actually covers
Firm management software is far more than bookkeeping production. The modules that drive the quote are DMS (document management), time tracking, invoicing and engagement letters, electronic signature and the client portal. Here are the 2026 orders of magnitude for a custom-built module.
| Module | Custom build cost (EUR excl. tax) | Vendor equivalent (per month) |
|---|---|---|
| DMS + auto-filing | 8,000 - 15,000 | included |
| Time tracking | 5,000 - 10,000 | 8 - 15 EUR/staff |
| Invoicing + engagement letters | 6,000 - 12,000 | 10 - 20 EUR/staff |
| Qualified e-signature | 4,000 - 8,000 | 2 - 5 EUR/signature |
| Client portal | 8,000 - 18,000 | 15 - 30 EUR/staff |
| Reporting & dashboards | 4,000 - 9,000 | partly included |
Off-the-shelf or custom: the break-even
The real question is not the sticker price but the total cost over 3 years. Take a 12-staff firm and compare.
| Item | Vendor (12 staff) | Custom |
|---|---|---|
| Year 1 | 12,960 EUR (90 x 12 x 12) | 55,000 EUR (build) |
| Year 2 | 12,960 EUR | 8,000 EUR (maintenance) |
| Year 3 | 12,960 EUR | 8,000 EUR |
| 3-year total | 38,880 EUR | 71,000 EUR |
| 5-year total | 64,800 EUR | 87,000 EUR |
| Data ownership | no | yes |
At 12 staff, the vendor stays cheaper until ~5 years. Custom wins faster once the firm passes 20 staff or bills the client portal as a differentiating service.
Mini case study
Marc, partner at an 18-staff firm in Nantes, currently pays 85 EUR per staff member per month, i.e. 18,360 EUR/year. Over 3 years he will spend 55,080 EUR without ever owning the tool. A custom quote comes in at 68,000 EUR + 9,000 EUR/year maintenance, i.e. 86,000 EUR over 3 years. Pricier at first, but from year 4 custom costs 9,000 EUR/year versus 18,360 EUR: the gap closes in 4.2 years, and Marc recovers data ownership plus a branded portal that helps retain clients.
FAQ
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How much does accounting firm software cost in 2026?
Between 40 and 90 EUR per staff member per month off-the-shelf, or 35,000 to 80,000 EUR one-shot for a custom platform, plus 8,000 to 12,000 EUR/year maintenance.
From how many staff is custom profitable?
Generally from 15 to 20 staff over a 3-year horizon. Below that, the vendor subscription stays cheaper unless you have a specific need.
Is 2026 e-invoicing included?
It must be. Check Factur-X format compliance and connection to certified platforms, whether with a vendor or in a custom spec.
Can we migrate without losing history?
Yes. A properly scoped data migration (DMS, clients, engagements) is 10 to 20 % of the project budget and is planned upfront to avoid any service disruption.
Is the client portal really worth it?
Yes: it cuts email back-and-forth by 30 to 50 % and secures document exchange. It is often the argument that justifies a branded custom build.
Let's scope your project. Tell us your headcount, priority modules (DMS, time, portal) and indicative budget, and we will price build and maintenance. 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.
