The verdict in three sentences
Delivery is not the end of the project, it is the start of its useful life: software without a maintenance contract degrades in 12 to 24 months under the pressure of security, browser and dependency updates. Negotiate three things in the contract: a corrective warranty of 3 to 12 months, a maintenance fee quantified as a percentage of the build, and written response SLAs. Without these clauses, every incident becomes an emergency negotiation at premium rates.
Warranty, maintenance, on-call: what are we talking about?
These terms cover different scopes that must be distinguished so you neither pay twice nor believe covered what is not. 2026 benchmarks.
| Service | Scope | 2026 benchmark |
|---|---|---|
| Corrective warranty | Fix delivered bugs | 3 to 12 months included |
| Maintenance (support) | Corrective + evolutive + adaptive | 8 to 18% of build/year |
| Response SLA | Time to take charge | 4 h to 48 h by criticality |
| Evolution quota | Small changes included | 1 to 3 days/month |
| On-call | Support outside business hours | +20 to 40% of the fee |
For software built at 100,000 EUR, maintenance at 12% represents 12,000 EUR/year, i.e. 1,000 EUR/month: the price of peace of mind against inevitable vulnerabilities and changes.
Response SLAs by criticality
An SLA without levels is a useless SLA. Define incident categories with quantified response and resolution times, so a blocking bug does not wait as long as a cosmetic typo.
| Level | Example | Time to take charge | Target resolution |
|---|---|---|---|
| P1 blocking | App inaccessible | 4 business hours | 1 business day |
| P2 major | Key feature down | 8 business hours | 3 business days |
| P3 minor | Comfort bug | 48 business hours | Next batch |
| P4 evolution | Add request | Quote within 5 days | Per schedule |
Write these thresholds into the contract with penalties if the commitment is not met: that is what turns a sales promise into a real obligation.
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Mini case study
Karim, director of a trading SME in Dublin, had an in-house ERP built at 120,000 EUR. He hesitates to sign the maintenance offered at 15% (18,000 EUR/year). He declines the first year to save money. Result: 3 uncovered incidents (a security update, a banking integration outage, a billing bug) handled as emergencies at 1,800 EUR each, plus 2 days of billing downtime estimated at 6,000 EUR in cash-flow delay. Total incurred: 11,400 EUR for partial and stressful coverage. Maintenance at 18,000 EUR/year would have covered everything with guaranteed SLAs. The apparent saving became a poorly controlled risk.
FAQ
What is the difference between warranty and maintenance? The warranty fixes delivered bugs for free during 3 to 12 months. Maintenance is an annual contract that additionally covers evolutions and adaptations to technical changes.
How much does maintenance cost in 2026? Between 8 and 18% of the build cost per year. For software at 100,000 EUR, count 8,000 to 18,000 EUR/year depending on service level and on-call.
What happens without maintenance? The software degrades in 12 to 24 months: unpatched vulnerabilities, browser incompatibilities, obsolete dependencies. Every incident becomes a one-off intervention at premium rates.
Do I need 24/7 on-call? Only if downtime is expensive for you (e-commerce, critical service). It adds 20 to 40% to the fee; otherwise a business-hours SLA is enough.
What should a good support contract contain? A dated warranty, maintenance as a percentage of build, SLAs per criticality level with penalties, an evolution quota and on-call terms. Each item must be quantified.
Let's scope your project. Share the value of your build and your tolerance to downtime, and we will build a calibrated warranty and maintenance contract. 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.
