You’ve signed off the build, the product is live, and the invoice is settled. Then, six months later, a dependency needs patching, the hosting bill creeps up, and a client asks for a small tweak that turns out not to be so small. If nobody budgeted for any of that, it lands as a surprise — and surprises make founders distrust the studio that built the thing in the first place. This article is for founders and product leads who’ve either just shipped or are about to, and want a realistic answer to one question: what will software maintenance costs actually be, and how much should you set aside to keep things running well?
Why software maintenance costs get forgotten
Most software maintenance cost conversations happen too late, because the build itself absorbs all the attention during scoping. Everyone agrees a fixed price or timeline for version one, and the assumption — often unspoken — is that once it ships, the spending stops. It doesn’t. A production application needs ongoing security patching, dependency upgrades, monitoring, bug fixes and small improvements for as long as it’s in use. Treat that as a one-off “we’ll deal with it later” line item and you’ll deal with it later, at the worst possible moment: usually a security alert, a broken integration, or a framework going end-of-life.
The fix is simple in principle: agree a maintenance budget alongside the build budget, before the contract is signed, not after launch. It doesn’t need to be precise to the pound — it needs to exist.
What “maintenance” actually covers
It helps to unpack the term, because “maintenance” gets used loosely. In practice it covers several distinct activities:
- Security and dependency updates — patching libraries and frameworks before known vulnerabilities become exploitable ones.
- Hosting and infrastructure — servers, databases, storage and CDN costs, which usually grow with usage.
- Monitoring and incident response — knowing something’s broken before a customer tells you, and having someone able to act on it.
- Bug fixes — the inevitable edge cases real users find that testing didn’t catch.
- Small enhancements — the minor changes that keep the product matching how the business has moved on since launch.
Some of this is genuinely fixed cost (hosting), some is proactive and scheduled (dependency updates), and some is reactive and unpredictable (incident response). A sensible maintenance plan budgets for all three, rather than assuming the reactive bucket will stay empty.
A sensible rule of thumb
There’s no single correct number, because it depends heavily on the size and complexity of the system, how much it’s used, and how much technical debt was already baked in at launch. That said, a widely cited industry benchmark — sometimes referred to informally as the Gartner rule — puts annual maintenance spend at somewhere around 15–25% of the original build cost, with more complex or heavily customised systems sitting towards the higher end. Infrastructure alone tends to be the smallest slice; the bulk goes on the people-time spent keeping dependencies current, responding to issues, and making the small improvements a live product always needs.
That percentage is a planning tool, not a promise. A simple marketing site with low traffic will cost a fraction of that to maintain. A multi-tenant SaaS platform handling customer data and payments will sit at the higher end, partly because the cost of getting maintenance wrong — a breach, an outage, a broken billing flow — is so much higher too. If you want an accurate figure for your own project rather than an industry average, that’s a conversation worth having explicitly with whoever quotes the build — see our guide to how much bespoke software costs in the UK for how build estimates are usually put together, and ask for the maintenance estimate in the same conversation.
Retainer or ad hoc — which model fits
Once you’ve got a rough number in mind, the next decision is how you buy the work. Broadly there are two models:
Ad hoc support means paying for time only when something needs doing — a bug fix here, a small feature there. It’s flexible and there’s no ongoing commitment, which suits products with genuinely light, unpredictable needs. The trade-off is that nobody is proactively watching the system between requests, and hourly rates for reactive, urgent work tend to run higher than planned work.
A retainer buys a set number of hours each month, usually with security monitoring, dependency updates and a defined response time built in. It costs more when nothing goes wrong, and pays for itself the first time something does — because the person fixing it already knows the codebase, rather than starting from zero under pressure. For anything handling customer data, payments, or business-critical workflows, a retainer is almost always the safer default.
This is really the same decision as the one covered in our piece on choosing between a fixed-scope project and a dedicated team — it’s a question of how predictable your ongoing needs are, and how much you value having the same engineers available when something breaks.
Build the ops habits in from day one
The single biggest lever for keeping maintenance costs down isn’t the contract model — it’s what shipped on launch day. A product with decent logging, error tracking and basic uptime monitoring in place from the start is dramatically cheaper to maintain than one where the first maintenance task is figuring out what’s actually happening in production. If you haven’t already, it’s worth reading our guide on what to monitor before you scale — most of it costs very little to set up early and saves real money later, because problems get caught while they’re still small and cheap to fix.
Technical debt is a stealth maintenance cost
Every codebase accumulates shortcuts taken under deadline pressure — that’s normal, and not automatically a problem. It becomes a maintenance cost when nobody tracks it, and the interest quietly compounds until a routine feature request takes three times longer than it should. Rolling a small, deliberate allowance for addressing technical debt into the maintenance budget — rather than treating it as a separate emergency project every couple of years — keeps that interest rate manageable. We’ve written more on how to prioritise technical debt without stalling the roadmap, which is worth reading alongside this if debt has already built up.
Getting the number into the original quote
The cleanest way to avoid the post-launch surprise is to ask for the maintenance estimate at the same time as the build quote, not after. A studio that can only price the build and shrugs at what comes next is telling you something about how they think about the product’s lifecycle. Ask specifically: what’s included in a standard support retainer, what counts as a billable extra, and what response time you get for a genuine incident versus a minor request. Those answers tell you far more about the real cost of ownership than the headline day rate.
If you’re weighing this up for a project that hasn’t started yet, our pricing page sets out how we structure both fixed-scope builds and ongoing retainers, so you can see build and maintenance costs side by side rather than discovering the second one later.
FAQ
How much should I budget for software maintenance after launch?
As a planning benchmark, expect somewhere around 15–25% of the original build cost per year, with simpler products towards the lower end and complex, data-heavy systems towards the higher end. Treat it as a starting estimate and ask your development partner to refine it for your specific product.
What’s the difference between software maintenance and software support?
Maintenance is the ongoing technical work of keeping a system secure, up to date and running well — patches, monitoring, bug fixes. Support is usually the response side: helping users, triaging issues and agreeing what gets fixed and when. In practice most retainers bundle both together.
Is a maintenance retainer worth it for an early-stage startup?
If the product handles customer data, payments, or anything business-critical, yes — a modest monthly retainer is usually cheaper than an emergency fix under pressure, and it means the same engineers who know the system are the ones responding. For a very low-traffic, low-risk product, ad hoc support can be a reasonable starting point.
Should maintenance costs be discussed before development starts?
Yes. Agreeing the maintenance model and a rough budget alongside the build quote avoids the common situation where founders have planned carefully for launch but not for the years the product will actually run afterwards.
If you want a clear-eyed estimate of what both the build and the maintenance of your product would realistically cost, book a free consultation and we’ll talk it through.
Related: Cloud Cost Optimisation for Startups: A Founder’s Guide — a practical look at where hosting spend leaks away and how to bring it back under control.
