Most software quotes describe one thing: getting to launch. That is the number that gets compared across vendors, and it is the number that gets approved. It is also the smaller half of what the system will cost you.
What actually recurs
A running system carries costs whether or not anyone is actively working on it. In rough order of how often they surprise people:
- Hosting and database — modest for a brochure site, meaningful the moment you have real traffic or real data
- Domain and TLS certificate renewals, which are small but cause outages when missed
- Third-party services — payment gateways, SMS and email delivery, mapping, analytics — each with their own pricing curve
- Dependency and framework upgrades, which are not optional: unpatched libraries are how most sites get compromised
- Backups, and the storage they consume, which grows every month
- The steady trickle of small changes — a new field, a changed price, a report someone now needs
A usable rule of thumb
For a custom-built system, budget fifteen to twenty-five per cent of the original build cost per year to keep it healthy. Below that figure you are not maintaining the system, you are deferring its maintenance, and deferred maintenance is paid later with interest.
That percentage is not a support retainer somebody invented. It is roughly what it costs to keep dependencies current, respond to the platform changes that arrive uninvited, and absorb the small change requests that every working system generates.
What to ask before you sign
- What does hosting cost per month, at the traffic we expect in year two — not year one?
- Which third-party services does this depend on, and what do they charge as we grow?
- Who applies security updates, how often, and is that inside or outside the quoted price?
- What happens to the code if we stop working with you?
A vendor who cannot answer the last question quickly is telling you something important about the second year.
- Budgeting
- Software