Custom app support and maintenance SLA pricing in London

The verdict in three sentences

Application support and maintenance for a business app comes down to three variables: the scope covered (corrective, preventive, enhancements), the guaranteed response times and reversibility at the end of the contract. IT services firms commonly charge 15 to 20 % of the build cost per year, with day rates of 550 to 850 EUR for enhancements. At Kolonell, maintenance is a flat fee of 35,000, 75,000 or 120,000 FCFA a month (50, 110 or 180 EUR) excluding new features, which clearly separates keeping the app running from the development budget.

What application support costs in 2026: three models

The IT director of a 400-employee company in London who had a scheduling application built for 60,000 EUR usually receives one of these three proposals at renewal.

Compare carefully: Kolonell plans cover corrective and preventive maintenance (security updates, dependencies, backups, monitoring, bug fixes) but not functional enhancements, which are quoted separately. Percentage-based IT firm contracts often include a small enhancement allowance, hence the gap. To compare like for like, always separate corrective work from enhancements.

Service levels, penalties and reversibility

A support contract is only worth its measurable commitments. An SLA without penalties or tracked indicators is just an intention.

Reversibility is the most neglected clause. Require ownership of the source code, permanent access to the Git repository, up-to-date operations documentation and a commitment to support the incoming provider for 1 to 3 months at a fixed price.

Choosing the right plan by criticality

A scheduling app that halts the shop floor when it goes down should not be treated like an internal tool opened once a week.

Mini case study

Helen, IT director of a logistics company in London, pays her IT firm 11,400 EUR a year for support, i.e. 19 % of a 60,000 EUR build, with 5 enhancement days included. She actually uses 12 enhancement days a year, 7 of them billed on top at 700 EUR a day, i.e. 4,900 EUR. Real budget: 16,300 EUR a year. By splitting the two items, a Premium maintenance plan at 2,160 EUR a year plus 12 quoted enhancement days gives her a budget she can manage line by line. Even with enhancements valued at 650 EUR a day (7,800 EUR), the total reaches 9,960 EUR, about 6,300 EUR saved per year, with a 4 business hour response on blocking incidents.

FAQ

What share of the build cost should we budget for support?

The market benchmark remains 15 to 20 % of the build cost per year with an IT firm, light enhancements included. A pure maintenance plan, such as Kolonell's at 50 to 180 EUR a month, costs much less but excludes enhancements.

What response time should we require for a critical app?

Aim for a response within 4 business hours at most and a fix or workaround within 1 business day for a blocking incident. Below 2 hours, cost rises sharply because it implies on-call staff.

How are penalties calculated?

Most commonly 2 to 5 % of the monthly fee per recorded breach, capped at 15 to 20 % a year. Insist on an indicator measured by a shared ticketing tool, otherwise the penalty cannot be verified.

Can we switch provider mid-contract?

Yes if the reversibility clause is written: source code, repository access, documentation and 1 to 3 months of handover support. Without it, a takeover often costs the new provider 10 to 20 days of audit.

Are enhancements included in Kolonell plans?

No. The 35,000, 75,000 and 120,000 FCFA monthly plans cover corrective, preventive, security and monitoring work. Enhancements are quoted separately, which keeps the budget predictable.

Let's scope your project. Send us a description of your application, user count and expected response times: we will recommend the right plan and price your enhancement volume through our free quote form. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.