The verdict in three sentences
For an SME business application, a maintenance retainer costs between 800 and 3,500 EUR excl. VAT per month in 2026 and fits when the volume of requests is stable and predictable. Time and materials, billed at 550 to 750 EUR per day, stays more flexible but shifts all overrun risk onto you. Whatever the model, a contract without measurable KPIs (fix time, regression rate) or a reversibility clause makes you dependent on your provider.
Retainer, time and materials, work units: the three models compared
Application maintenance covers corrective work (bugs), preventive work (security updates, dependencies) and evolutive work (new features). The billing model decides who carries the risk.
| Criterion | Monthly retainer | Time and materials | Work units |
|---|---|---|---|
| 2026 price (SME, France) | 800 to 3,500 EUR excl. VAT per month | 550 to 750 EUR excl. VAT per day | 300 to 900 EUR per unit depending on complexity |
| Budget predictability | high | low | medium to high |
| Overrun risk | carried by the provider | carried by the client | shared, based on the price grid |
| Commitment on lead times | yes, through SLAs | rarely | yes, per unit type |
| Best for | stable app, 5 to 30 requests per month | redesign, high uncertainty | recurring, well-typed changes |
| Usual term | 12 to 36 months | on demand | 12 to 24 months |
| Common trap | oversized retainer left unused | days billed with no deliverable | poorly calibrated grid |
Work units are an effective compromise: each request is classified (simple, medium, complex) with a price and lead time set in advance. For example, a simple screen change at 1 unit, a new report at 3 units, an API connector at 8 units.
The KPIs to require in the contract
A serious maintenance contract sets commitments measured monthly, with capped penalties (often 5 to 15% of the monthly fee). Here are realistic levels for an SME in 2026.
| KPI | Expected level | Indicative penalty |
|---|---|---|
| Response time for a blocking incident | under 2 business hours | 5% of the fee if missed |
| Fix time for a blocking incident | under 8 business hours | 10% of the fee |
| Fix time for a major incident | 2 business days | 5% of the fee |
| Regression rate after release | under 5% of releases | action plan within 15 days |
| Application availability | 99.5% to 99.9% per month | 5 to 10% of the fee |
| Critical dependency updates | within 30 days of release | mandatory monthly report |
| Automated test coverage | at least 60% on critical code | quarterly review |
Also require a monthly dashboard (tickets opened, closed, actual lead times, days used) and a quarterly review. Without this data, you cannot tell whether the retainer is correctly sized.
The reversibility clause: your exit insurance
Reversibility organises the takeover of the application by you or another provider. It must include permanent access to the source code repository, up-to-date technical documentation, access to environments and a transition period of 1 to 3 months. Its cost is usually 5,000 to 15,000 EUR excl. VAT, to be set at signature rather than in the middle of a dispute.
Finally, check that the contract grants you ownership of the code developed and that hosting credentials (cloud, domain name, app stores) are in your name.
Mini case study
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Julien, application manager at an 80-employee distribution SME in Nantes, paid for maintenance on time and materials at 650 EUR per day. Over the last 12 months he used 42 days, i.e. 27,300 EUR excl. VAT, with big swings (2 days some months, 9 days others) and no lead-time commitment.
He negotiates a retainer of 2,000 EUR excl. VAT per month covering 3 days a month of fixes and small changes, with SLAs, i.e. 24,000 EUR excl. VAT per year. Extra needs go through work units at 600 EUR each: he estimates 6 units a year, i.e. 3,600 EUR. Total: 27,600 EUR excl. VAT, almost the same budget, but with guaranteed lead times, a monthly dashboard and reversibility priced at 8,000 EUR. The real gain is the end of blocking incidents left open for 3 days.
FAQ
What maintenance budget should I plan relative to development cost?
The common rule puts annual maintenance at 15 to 25% of the initial development cost. An 80,000 EUR application therefore needs about 12,000 to 20,000 EUR excl. VAT of maintenance per year.
What happens to unused retainer days?
Negotiate a carry-over to the next quarter, capped at 20 to 30% of the retainer. Without a carry-over clause, an oversized retainer ends up costing more than time and materials.
Is time and materials always more expensive?
No, for a very stable application needing fewer than 15 days a year, time and materials at 650 EUR (about 9,750 EUR) costs about the same as a minimal 800 EUR monthly retainer (9,600 EUR), but without commitments. The difference lies in guaranteed lead times.
How long does a maintenance handover to a new provider take?
Allow 4 to 8 weeks of transition for a mid-sized application, including 5 to 10 days of code audit. The audit budget is between 3,000 and 7,000 EUR excl. VAT.
Are security updates included?
They should be included in a maintenance retainer, with a maximum of 30 days for critical dependencies. On time and materials, they are billed by the hour, often 1 to 2 days per quarter.
Let's scope your project. We audit your application, size a retainer or a work-unit grid (indicative budget of 800 to 3,500 EUR excl. VAT per month) and draft measurable SLAs, with a takeover in 4 to 8 weeks. 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.
