The verdict in three sentences
Hourly maintenance with no guaranteed response time is the most expensive contract for a 150-employee company: you pay for every intervention and you wait when the site goes down. A fixed retainer of EUR 350 to 1,000 a month, with 3 to 8 hours of changes and a 4 business-hour response on critical incidents, often costs less over the year and makes the provider accountable. Four clauses make the difference: reversibility, code ownership, penalties and monthly reporting.
The three retainer tiers in 2026
Amsterdam agencies price slightly above the Dutch average, with an hourly rate of EUR 85 to 115 excluding VAT for changes.
| Tier | Monthly fee excl. VAT | Included | Response time |
|---|---|---|---|
| Basic maintenance | EUR 90 to 175 | CMS and plugin updates, daily backups, uptime monitoring | 2 business days |
| Maintenance + changes | EUR 350 to 575 | basic + 3 to 4 hours of changes, unlimited bug fixing | 8 business hours |
| Corporate retainer | EUR 700 to 1,000 | basic + 6 to 8 hours, on-call, monthly report, quarterly review | 4 business hours on critical incidents |
| Extra hours | EUR 85 to 115 per hour | beyond the bundle, on approved quote | per schedule |
| Weekend on-call | EUR 175 to 350 a month, optional | critical incidents outside business hours | 2 to 4 hours |
| Takeover audit (new provider) | EUR 1,400 to 2,900 one-off | code, security and documentation audit | 1 to 2 weeks |
Unused hours rarely roll over beyond a month or two. Negotiate quarterly rollover: it is a common request and usually accepted.
Defining service levels (SLA)
A useful SLA ranks incidents by severity and sets a response time and a resolution time for each.
| Severity | Example | Response | Target resolution | Indicative penalty |
|---|---|---|---|---|
| Critical | site down, contact form failing | 4 business hours | 1 business day | 5% of monthly fee per day late |
| Major | key page broken, load time above 5 seconds | 1 business day | 3 business days | 2% per day |
| Minor | typo, badly cropped image | 3 business days | next release | none |
| Security | published vulnerability in a plugin in use | 1 business day | 2 business days | 5% per day |
| Monthly uptime | measured by a third-party tool | 99.5% to 99.9% commitment | over the month | 10% of fee if missed |
Cap penalties at 20 to 30% of the monthly fee: beyond that, no serious provider will sign, and the goal is responsiveness, not collecting penalties.
Clauses to require
Reversibility: at the end of the contract, the provider hands over code, database, access and up-to-date documentation within 15 days, and supports the incoming provider for 2 to 5 days billed at the contract rate. Code ownership: custom code built for you belongs to you, open source components stay under their licences. Monthly report: updates applied, incidents and actual response times, hours used, recommendations. Term and termination: 12-month maximum commitment, automatic renewal with 2 to 3 months' notice. Access: admin accounts in your company's name with the host and the domain registrar.
Mini case study
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Sanne, digital manager of a 150-employee company in Amsterdam, paid for maintenance by the hour: 42 hours a year at EUR 100, i.e. EUR 4,200, with no guaranteed response. Two quote-form outages lasted 3 and 5 days, during which about 10 enquiries were lost, with an average deal of EUR 4,500 and a 25% close rate, an estimated EUR 11,250 shortfall. She signs a EUR 500 monthly retainer with 4 hours of changes and an 8 business-hour response, i.e. EUR 6,000 a year. The EUR 1,800 extra cost is easily covered if the contract prevents even one long outage.
FAQ
What is the difference between maintenance and an application support retainer?
Maintenance covers security, updates and backups. An application support retainer adds changes, bug fixing and a service commitment, usually from EUR 575 a month.
Can we switch providers mid-contract?
Yes, by respecting the notice period, often 2 to 3 months. The reversibility clause guarantees you get code and access back within 15 days with no hidden fees.
How do we check updates are really done?
Require a monthly report listing installed versions and tested backups. A third-party monitoring tool at EUR 10 to 30 a month also measures uptime independently.
Is a 4-hour SLA realistic for an SMB?
Yes in business hours, with an agency of at least 3 to 4 developers. For a solo freelancer, aim for 8 business hours or add a documented backup arrangement.
Should hosting be included in the maintenance contract?
It is convenient to have a single accountable party, but the hosting subscription must stay in your name. Budget EUR 15 to 120 a month depending on host and traffic.
Let's scope your project. Send us your current contract and last 12 months of invoices: we propose the right service level, with SLA, reversibility and an indicative monthly budget compared with your actual cost. 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.
