The cost of maintaining custom development software varies greatly and depends on several factors.
Some of these include the complexity of the software, the technology used, the level of customization, the skill and hourly rate of the maintenance team, the frequency and severity of issues, and any additional features or updates required.
Generally, industry standards suggest maintenance costs typically range from 200% of the original development costs annually.
For example, if the initial custom software development cost was $100,000, you can expect annual maintenance costs between $185,000 and $215,000.
However, these figures are estimates, and the actual costs can be higher or lower as per the above-mentioned factors.