# Software maintenance: what it includes and what it costs

*By Mohammed Hesham, Founder · Fix & maintain · published 20 October 2026*

## The short answer

Software maintenance is everything that keeps software working after launch: fixing bugs, updating frameworks and dependencies, patching security issues, adapting to new browsers, devices and integrations, and improving performance. A common rule of thumb puts it at 15–25% of the original build cost per year; most businesses pay for it as a fixed monthly care plan.

## Key takeaways

- Maintenance starts the day software goes live — it isn’t optional.
- Four kinds of work: fixing, adapting, improving and preventing.
- Budget roughly 15–25% of the build cost a year, adjusted for how much the software changes.
- A fixed monthly care plan is cheaper than paying for emergencies.

## What software maintenance includes

- Bug fixing: errors users report and errors monitoring catches first.
- Security: patching vulnerabilities, rotating keys, reviewing access.
- Updates: frameworks, libraries, runtimes and servers kept within support.
- Compatibility: new browsers, operating systems, devices and API versions.
- Performance: queries, pages and reports that slow down as data grows.
- Backups and monitoring: tested restores, uptime and error alerts.
- Small improvements: the changes users ask for once they use the software every day.

## The four types of software maintenance

The international standard for software maintenance (ISO/IEC/IEEE 14764) describes four types. Corrective maintenance fixes faults. Adaptive maintenance keeps software working as its environment changes — a new operating system, a payment provider’s new API. Perfective maintenance improves performance and usability. Preventive maintenance fixes problems before they show up, such as outdated dependencies or code that is hard to change safely.

In practice a good care plan mixes all four, with security and preventive work scheduled rather than left for a crisis.

## What it costs

A widely used rule of thumb is that maintaining software costs about 15–25% of its original development cost every year. A small, stable internal tool sits at the low end; a customer-facing platform that handles payments, personal data or frequent changes sits at the high end — or above it.

The cheapest way to pay for it is a fixed monthly plan with a set number of hours, agreed after an audit of the current state of the software. The most expensive way is waiting until something breaks.

## Signs your software is under-maintained

- Frameworks or servers are out of their support window.
- Fixed bugs come back, or a small change breaks something unrelated.
- Nobody knows when the last backup was restored to test it.
- Pages and reports keep getting slower.
- Only one person knows how to deploy it.

## Can someone else maintain software you didn’t build with them?

Yes. Taking over existing software starts with an audit: reading the code, the infrastructure and the deployment, then listing what is risky and what to fix first. From there, maintenance is the same as for software the team built itself.

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