Custom SaaS Maintenance: What TMA Really Costs (2026)

The verdict in three sentences

The total cost of ownership of a custom app is the great budget omission: application maintenance runs to 12 to 20% of the build cost per year, i.e. EUR 9,600-16,000 for an app built at EUR 80,000. On top come hosting/monitoring (EUR 150-500/month) and annual enhancements. Choosing between a retainer and time-and-materials (day rate EUR 500-700) depends on your predictable volume of changes.

What maintenance actually covers

Maintenance is not just a bug "safety net". It bundles corrective work, light enhancements, security and availability.

A simple rule: beyond 18 months, an unmaintained app accumulates technical debt (obsolete dependencies, vulnerabilities) whose catch-up often costs more than regular maintenance. Budgeting maintenance from the build is the most profitable decision.

Retainer vs time-and-materials: the 2026 comparison

Two models coexist. The monthly retainer smooths cost and includes an SLA; time-and-materials (billed per day) is more flexible but less predictable.

A typical SLA distinguishes severity levels: critical fix (app down) within 4 h, major within 1 business day, minor scheduled. Require hosting, backups and monitoring to be included or clearly billed separately — a frequent source of nasty surprises.

Mini case study

Mark, MD of an industrial SME, had a production-management app built for EUR 80,000. He had provisioned nothing for the aftermath. Maintenance quote: retainer EUR 1,500/month (critical-fix SLA < 4 h), hosting + monitoring EUR 300/month = EUR 21,600/year. In parallel he budgets 15 days of time-and-materials at EUR 600/day for annual enhancements = EUR 9,000. Annual cost of ownership: EUR 30,600, about 38% of the build. A high figure, but one that protects an EUR 80,000 asset used daily by 40 employees.

FAQ

What percentage of the build should I plan for maintenance?

A 2026 ballpark of 12 to 20% per year, excluding major enhancements. Below 12% you only cover corrective work; enhancements pile up as technical debt.

Retainer or time-and-materials: which to choose?

Retainer if you have regular changes and want a predictable SLA. Time-and-materials if your needs are occasional. Many combine both: retainer for the run, T&M for enhancement projects.

What should a good SLA contain?

Severity levels with response times (e.g. critical < 4 h), a coverage window (business hours or 24/7), and penalties for breaches. Without quantified times, an SLA is cosmetic.

Is hosting included in maintenance?

Not always. Allow EUR 150-500/month depending on load and redundancy. Check that backups and monitoring are included, otherwise budget them separately.

Can I stop maintenance to save money?

Short term yes, but technical debt accumulates: obsolete dependencies, security flaws, incompatibilities. Catch-up often costs more than continuous maintenance.

Let's scope your project. Give us the build cost, number of users and desired SLA level: we price a fitting maintenance retainer + hosting. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.