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Build vs Buy Accounting Practice Software for Outsourced Firms (2026)

Mohamed Bah·Fondateur, Kolonell
September 9, 2026
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Build vs Buy Accounting Practice Software for Outsourced Firms (2026)

Build vs Buy Accounting Practice Software for Outsourced Firms (2026)

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The verdict in three sentences

An off-the-shelf suite costs 45-120 EUR per staff member per month in 2026, a 5-year TCO of 150,000-220,000 EUR for a 25-person firm. A custom build lands at 90,000-180,000 EUR plus support, and becomes competitive once a firm exceeds 20-25 staff. The real trade-off is not only price: it is vendor lock-in and data reversibility.

License vs build: the direct cost

The vendor model bills per usage and grows mechanically with headcount. Custom is an amortized upfront investment. Here are the 2026 orders of magnitude.

CriterionOff-the-shelf suiteCustom build
Entry cost0 - 5,000 EUR (setup)90,000 - 180,000 EUR
Recurring cost45 - 120 EUR/staff/monthSupport 1,500 - 3,000 EUR/month
Annual cost (25 staff)13,500 - 36,000 EUR18,000 - 36,000 EUR (support)
ExtensibilityVendor roadmapFull, on demand
Code ownershipNoYes
Data reversibilityPartial (limited export)Full (owned schema)

5-year TCO for 25 staff

The reasoning flips over time. With a median license at 80 EUR/staff/month, the vendor suite costs 25 x 80 x 12 = 24,000 EUR/year, or 120,000 EUR over 5 years, excluding price hikes (often 3-6%/year) and options.

Scenario (5 years, 25 staff)Cumulative cost 2026Note
Vendor low license (45 EUR)~67,500 EURNarrow scope
Vendor median license (80 EUR)~120,000 EUROptions excluded
Vendor high license (120 EUR)~180,000 EURFull modules
Custom (build 120,000 + support 2,000/mo)~240,000 EURCode owned
Custom (build 90,000 + support 1,500/mo)~180,000 EURTarget tier

Custom is not always cheaper in cash, but it removes vendor lock-in, guarantees reversibility, and amortizes better as the firm grows: each new hire costs 0 EUR in license.

Mini case study

Mr. Bernard, managing partner of a 25-person firm, currently pays 26,000 EUR/year in vendor licenses. Over 5 years, with a 4% annual price hike, he spends about 141,000 EUR. A custom build at 95,000 EUR plus 1,600 EUR/month support comes to 191,000 EUR over 5 years. It is 50,000 EUR more, but he owns the code, controls his data, and has no marginal cost per hire: at 35 staff in year 4, the vendor suite would have cost 40% more, flipping the equation.

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What does an off-the-shelf practice suite cost in 2026?

Between 45 and 120 EUR per staff member per month depending on active modules. For a 25-person firm that is 13,500-36,000 EUR per year, excluding options and price hikes.

At what size does custom become relevant?

Generally above 20-25 staff, because license cost grows with headcount while the build is fixed. Each new hire then costs 0 EUR in extra license.

What is data reversibility and why does it matter?

It is the ability to recover all your data in a usable format if you switch tools. With a vendor suite the export is often partial; with custom, the firm owns its data schema.

Is custom always cheaper?

Not in immediate cash: over 5 years it can cost 30,000-50,000 EUR more than a median license. The advantage is code ownership, reversibility and no marginal cost per staff member.

Can we migrate gradually from a vendor suite to custom?

Yes, via a hybrid approach: build the high-value bricks first (portal, steering) and keep the vendor for production during the transition, with ledger/tax connectors.

Let's scope your project. Send us your staff count, current vendor bill and horizon (3, 5 or 7 years) and we will model your comparative TCO. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.

Tags:#build vs buy accounting software#accounting practice suite#practice software comparison#accounting software TCO#practice management license#vendor lock-in accounting#data reversibility#2026
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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.