What a Support Retainer for a Legacy .NET Application Actually Covers

A support retainer for a .NET application in maintenance mode costs $1,900 a month at Parka Software. That buys 10 hours. Twenty hours is $3,600 and forty is $7,000, which works out to $190, $180 and $175 an hour. All three run month to month with thirty days notice.

For comparison, a mid-level .NET developer at a $135,000 salary costs about $14,600 a month once tax, benefits and equipment are counted. That person is available every day, and a retainer is available during business hours within its block. If the application produces more than about forty hours of work a month, every month, hire the developer.

What fills the hours

The 10-hour tier fits a stable system that has to stay healthy. In a normal month the time goes to security patches, framework and package updates, and renewing certificates and credentials before they lapse. Some of it goes to monitoring, so a failed nightly job gets reported by an alert before a user finds it. The rest is investigation: a report that ran in four seconds last month now takes ninety, and someone has to find out why.

This work rarely shows up in a ticket queue, so it is easy to leave out of an estimate. A TLS certificate expires on a fixed date. A package the application depends on gets a security advisory. Both need a few hours whether or not the business asked for anything that month, and budgeting for them up front keeps the estimate accurate.

The 20-hour tier adds a steady flow of small changes: a new column on a report, a field added to a form, an integration adjusted because the vendor on the other end changed its API. This is the common tier for an application people still use daily and occasionally ask to have changed. Forty hours is roughly a day a week and suits a modernization track running beside the maintenance, or several connected systems under one arrangement.

Documentation is written as the work happens. Deployment steps, integration behavior, the business logic sitting in stored procedures and the order the scheduled tasks run in all get recorded, and the record belongs to the client if the arrangement ends.

Unused hours expire at the end of the month. A quiet month means the patches went in, nothing broke and no changes were needed. The fee reserved a person who already understands the system, and that was true whether or not the phone rang.

Where maintenance ends

A retainer covers keeping the application running and changing it in small, safe steps. It does not cover a migration to a new framework version, a rewrite or a large new build. Each of those is a project with its own scope and price, quoted separately while the retainer continues alongside it.

Two other limits belong in writing before the first invoice. Response is during business hours, so a system that needs someone paged at 2 a.m. needs a different agreement. Work beyond the monthly block is billed at the standard hourly rate, and the client is told before it happens.

A retainer on an unfamiliar system starts with a fixed-fee assessment, so the learning happens once at a known price and the monthly hours go to the work. The assessment establishes what runs in production, what the database holds, what the external dependencies are and how deployment works.

Before asking anyone for a quote, count six things in your own environment:

1. Applications and the framework version each one targets.
2. Integrations with outside systems, and who owns the other end.
3. Scheduled jobs, and what happens to the business when one fails.
4. Certificates, API keys and service accounts, with their expiry dates.
5. Change requests the business made in the last twelve months.
6. Incidents in the same period, and how many hours each one took.

Items five and six give you the monthly hours. Add the requested changes to the incident hours, divide by twelve, and add four to six hours a month for routine patching and renewals. If the result is under fifteen, a 10-hour block with occasional overage will cover it. If it is over forty, the comparison with a full-time hire is worth running again.

Bring that list to whoever you are evaluating. It lets them quote from your numbers, and how to evaluate a software consultant covers what else to ask. The terms above are published on the support and maintenance page.