Website Maintenance and Support Retainer in London in 2026: What the Fee Covers

The verdict in three sentences

A B2B brochure-site maintenance retainer sits between 100 EUR/month (corrective + security) and 800 EUR/month (evolutive support with included hours) in 2026. Ad-hoc time-and-materials bills at 60 to 90 EUR/hour: it suits a stable site, the retainer a living one. The right question is not "how much" but "how many evolution hours and what SLA": a retainer with no restoration commitment nor included hours is probably oversized.

What each tier covers

A serious retainer always details its scope. Beware a "maintenance retainer" at 300 EUR/month that specifies neither evolution hours nor SLA: you are paying for air.

Unused evolution hours are sometimes rolled over, sometimes lost: check this, it changes the retainer's real value. A Pro tier with 3 rollover hours is worth more than a Premium with none.

SLAs: the real differentiator

The SLA (service level agreement) sets the reaction speed on an incident. It justifies the price gap between tiers far more than the number of backups.

For a lead-generating brochure site, a 24 h SLA is often enough: a weekend outage is fixed on Monday. A transactional or critical site justifies Premium at 4 h and 24/7.

Mini case study

Sophie, marketing lead at a B2B services SME in London, receives a support proposal at 600 EUR/month, i.e. 7,200 EUR/year. She finds it steep for a 12-page brochure site. On analysis she sees the retainer includes only 2 monthly evolution hours and a 24 h SLA: the scope matches a Pro tier billed as Premium. She renegotiates to a Pro retainer at 350 EUR/month (4,200 EUR/year) with 4 included, rollover hours, saving 3,000 EUR/year. Over the year she actually uses 28 evolution hours; on T&M at 80 EUR/h that would have cost 2,240 EUR plus corrective maintenance. The Pro retainer stays cheaper and more predictable. Sophie avoided oversizing by reading the scope line by line.

FAQ

Corrective maintenance vs support retainer, what's the difference?

Corrective maintenance covers security, backups and bug fixes (100-300 EUR/month). Evolutive support adds monthly evolution hours to keep the site moving (300-800 EUR/month). One keeps the site alive, the other makes it grow.

T&M or retainer: which to choose?

Time-and-materials (60-90 EUR/h) suits a stable site with few evolutions. The retainer pays off from 3-4 hours of regular monthly work, and adds an SLA and predictable budget.

What must the SLA guarantee?

At minimum a restoration time (4 to 24 h by tier) and an availability level (99.0 to 99.9%). A retainer with no written SLA does not protect you in a prolonged outage.

Are unused hours lost?

It depends on the contract: some roll hours over month to month, others reset them. A retainer with rollover is markedly better value, demand it in writing.

How do I tell if a retainer is oversized?

Compare the price to included hours and SLA. A 600 EUR/month retainer with only 2 hours and a 24 h SLA matches a Pro tier; you pay the Premium price without the scope.

Let's scope your project. Send us your current site and evolution needs and we will calibrate the right maintenance tier, neither under- nor oversized. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.