The verdict in three sentences
Budget maintenance from day one: expect 12 to 20 % of the build cost per year, hosting and security included. An unmaintained app accumulates technical debt and vulnerabilities; an uncontracted urgent fix costs 2 to 3 times more. The right move is to sign a support contract with an SLA matched to the app's criticality.
The maintenance cost lines to budget
Application maintenance is more than bugs. It covers fixes, enhancements, security and operations. Here are the main lines for an app built for EUR 50,000.
| Line | Content | 2026 order of magnitude/year |
|---|---|---|
| Corrective maintenance | Bugs, regressions | EUR 2,500 to 5,000 |
| Evolutive maintenance | Small enhancements, tweaks | EUR 3,000 to 6,000 |
| Security and updates | Patches, dependencies, audits | EUR 1,500 to 3,500 |
| Managed hosting | Servers, backups, monitoring | EUR 1,200 to 4,000 |
| Support and supervision | On-call, tickets, SLA | EUR 1,500 to 4,000 |
| Total (EUR 50,000 build) | EUR 6,000 to 10,000 (12-20 %) |
SLA levels and their response times
The SLA (Service Level Agreement) sets the response and resolution times by severity. The more critical the app, the higher the level and the price.
| SLA level | Response time | Blocking incident resolution | Indicative cost/year |
|---|---|---|---|
| Basic (business hours) | 8 h | 3 business days | EUR 3,000 to 5,000 |
| Standard (9am-7pm) | 4 h | 1 business day | EUR 6,000 to 9,000 |
| Business (6 days/7) | 2 h | 8 h | EUR 10,000 to 16,000 |
| Critical (24/7) | 30 min | 4 h | EUR 18,000 and up |
Mini case study
Sophie, CIO of a financial services SME in Lille, runs a client app built for EUR 90,000. In year one, with no support contract, two blocking incidents handled as emergencies cost her EUR 11,000 off-budget, plus a day of downtime. She then signs a Standard support contract at 15 % of the build, i.e. EUR 13,500/year, with a 4 h response SLA. The result: incidents handled on time, no prolonged downtime and a smoothed, predictable budget. Maintenance cost becomes a managed investment rather than an endured bill.
FAQ
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What annual budget for maintenance?
As a rule 12 to 20 % of the build cost per year. For a EUR 50,000 app, plan EUR 6,000 to 10,000, hosting and security included; more for a 24/7 SLA.
Can we skip a support contract?
Risky. Without one, every fix is billed on demand, often 2 to 3 times more, with no response commitment. A contract smooths cost and guarantees responsiveness.
What exactly does support cover?
Corrective (bugs), evolutive (small improvements), security (patches, dependencies) and often hosting and supervision. Large functional enhancements are quoted separately.
How do I choose my SLA level?
By criticality: a brochure site is fine with a basic SLA, while a payment app or client portal demands a business or 24/7 SLA with fast blocking-incident resolution.
Is hosting included in the contract?
Often yes in a managed offer. Budget EUR 100 to 350/month depending on traffic, backups and monitoring; isolate this line clearly in the contract.
Let's scope your project. Tell us your app's build cost and criticality level; we frame a support contract with a matched SLA, usually 12 to 20 % of the build per year. 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.
