B2B Website Maintenance & SLA Retainer in 2026: What a Support Contract Should Cover

The verdict in three sentences

An unmaintained B2B site is not free: it accumulates security debt and ends in an early rebuild at 18 months. A good support retainer is judged not by monthly price but by the SLA: time to restore, guaranteed uptime, backups and update scope. Pay for availability and responsiveness, not for a bucket of hours that expires every month.

Maintenance levels in 2026

Three levels stand out. Corrective maintenance covers bugs and security. An evolutive retainer adds small monthly changes. An hours bundle sells a volume of hours to consume, rolling over or not.

Beware non-rolling hours: if you don't consume, you lose. A bundle that rolls over 3 months smooths change peaks and avoids paying into the void.

The SLA: the clause that changes everything

The SLA (Service Level Agreement) defines your contractual guarantees. It is the real differentiator between a cosmetic contract and one that protects your B2B revenue.

Uptime of 99.5% allows 43 h of downtime per year. For a site driving critical B2B leads, aiming for 99.9% (8.7 h/year) is justified. Moving to Premium is costly but compares to the cost of a commercial outage.

The hidden cost of an unmaintained site

Without updates, a CMS accumulates vulnerabilities. An intrusion, a defacement or a site flagged dangerous by Google costs far more than a monthly retainer: cleanup 1,500-4,000 EUR, lost rankings, and often a forced rebuild at 18 months instead of 36. Maintenance is not a cost, it is insurance.

Mini case study

Sophie, marketing director of a B2B services SME in Dublin, is weighing a corrective plan at 250 EUR/month against a Standard retainer at 650 EUR/month. Her site absorbs 22 quote requests/month. An unpatched flaw causes a 3-day downtime and a 2,800 EUR cleanup, plus ~2 lost leads (~5,400 EUR of margin). The retainer's annual premium (4,800 EUR vs 3,000 EUR) is 1,800 EUR: a single avoided incident repays it more than four times over. She moves to a Standard retainer with 24h time-to-restore and daily backups.

FAQ

What's the difference between corrective maintenance and an evolutive retainer?

Corrective repairs and secures (150-400 EUR/month). An evolutive retainer adds monthly change hours (400-1,200 EUR/month) so the site evolves without a new quote for every change.

What is time-to-restore and why negotiate it?

It sets the maximum delay to bring the service back. It ranges from 72 h (basic) to 4 business hours (premium). For a commercial B2B site, aim for 24 h maximum.

Are bundled hours rollover?

Depends on the contract. Demand hours that roll over at least 3 months: otherwise every unused hour is forfeited monthly, inflating real cost by 20-30%.

Is hosting included in maintenance?

Not always. Managed, supervised OVH or Scaleway hosting costs an extra 50-150 EUR/month. Check whether it is included, re-billed or on your direct account.

What does an unmaintained site risk?

Security flaws, intrusion, Google blacklist and a forced rebuild at 18 months. A post-hack cleanup (1,500-4,000 EUR) far exceeds a year of corrective maintenance.

Let's scope your project. Tell us your site's criticality (leads/month, downtime tolerance) and we'll propose a calibrated SLA: corrective, retainer or premium with on-call. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.