The verdict in three sentences
A custom line-of-business tool without a maintenance contract (ATMM/support) is a time bomb: the real cost of ownership lands after go-live. For a 10-person accounting firm in Montreal, budget in 2026 an annual maintenance of 12 to 18 % of the build cost, plus managed hosting and backups. The right call is not fixed-fee or time-and-materials, but a baseline fixed fee covering corrective work and the SLA, topped up by T&M for enhancements.
Corrective, evolutive and hosting: the 2026 cost structure
Maintenance groups three blocks you must price separately. Corrective (bugs, security) is non-negotiable; evolutive (new tax rules, new statements) is the line item that overruns; hosting/backup guarantees continuity. On software delivered at 55,000 USD, the realistic annual range (2026 order of magnitude) is below.
| Item | % of build | Annual cost (base 55,000 USD) | Coverage |
|---|---|---|---|
| Corrective maintenance | 6-8 % | 3,300-4,400 USD | Bugs, security patches, hotline |
| Evolutive maintenance | 6-10 % | 3,300-5,500 USD | New tax rules, new statements |
| Managed hosting | — | 4,000-8,000 USD | Server, uptime, monitoring |
| Backups + DR | — | 2,000-4,000 USD | Daily backup, restore |
| Total maintenance + infra | 12-18 % | 12,600-21,900 USD | Full ownership/year |
A firm that budgets only the one-off discovers at month 13 that it is short 13,000-22,000 USD/year. Scoping maintenance in the contract avoids that cash gap.
Fixed-fee vs T&M and the SLA grid: what moves the price
The fixed fee smooths cost and secures the SLA; T&M (hourly rate 95-160 USD) is more flexible for one-off enhancements but unpredictable. The SLA — guaranteed response time — is the real price driver.
| Criterion | Fixed-fee maintenance | Time-and-materials | |
|---|---|---|---|
| 2026 indicative cost | 12,000-20,000 USD/year | 95-160 USD/hour | |
| Budget predictability | High | Low | |
| SLA included | Yes (4 h to 24 h) | No, best effort | |
| Best for | Corrective + continuity | One-off enhancements | |
| Critical patch delay | 48-72 h guaranteed | When available | |
| Overrun risk | Low | High | |
| SLA tier | Response time | Critical resolution | Annual uplift |
| Bronze | 24 business hours | 72 h | Included |
| Silver | 8 business hours | 48 h | +1,700 USD |
| Gold | 4 business hours | 24 h | +4,000 USD |
| Platinum | 2 h (7 days) | 8 h | +8,000 USD |
Mini case study
Mr. Tremblay, director of a 10-person accounting firm in Montreal, had his software built for 55,000 USD. He hesitates between no maintenance and a Silver fixed fee. An outage of the tax-return generation module during filing season would cost him, in lost person-days and client penalties, about 10,000 USD over 3 days. The Silver plan at 16,000 USD/year (maintenance + 8 h SLA) makes that outage nearly impossible: patch guaranteed within 48 h. Estimated avoided cost on one annual incident: 10,000 USD, not counting business continuity and client reputation.
FAQ
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What percentage of the build should I budget for maintenance in 2026?
Budget 12 to 18 % of the development cost per year, all included. On software at 55,000 USD, that is 12,600 to 21,900 USD annually.
How much is an hour of T&M in Montreal?
Between 95 and 160 USD depending on developer seniority. T&M suits one-off enhancements but becomes more expensive than a fixed fee beyond 60-70 hours/year.
Which SLA should an accounting firm choose?
A Silver SLA (8 h response, 48 h critical resolution) suffices for most firms. Move to Gold (4 h) only if the software is mission-critical during filing season.
Is hosting included in maintenance?
Not always. Managed hosting costs 4,000-8,000 USD/year and backups 2,000-4,000 USD. Require these line items explicitly in the contract.
Can we start without maintenance and add it later?
Technically yes, but every month without corrective work accrues security debt. Catching up often costs more than a fixed fee from go-live.
Let's scope your project. Tell us about your accounting software, its build cost and target SLA: we'll scope a maintenance plan for a firm of 5 to 20 staff. 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.
