How to Handle a Project With Mixed Billing Structures Inside Time-Trak

The Mixed Billing Problem Nobody Warns You About

You land a client. The initial project is flat fee. Then they add a monthly retainer. Then they ask for an hourly engagement on something outside the retainer scope.

Now you have three billing structures on one client. If your time tracker is not set up to handle that, every invoice becomes a reconstruction project.

This is common. Most established client relationships eventually develop mixed billing. The setup you do at the start of each engagement is what keeps it from becoming a mess.

Why One Project With One Rate Breaks Down

If you create a single project in Time-Trak for a client and log everything against it, the billing rate is uniform across all entries. That works fine for simple engagements. It fails the moment you have two types of work at two different rates running simultaneously.

Time-Trak handles this. You just need to use the structure it provides.

Use Separate Projects for Each Billing Structure

The cleanest approach is one project per billing arrangement. Flat fee project gets its own project entry. Retainer gets its own project entry with the retainer rate. Hourly overflow work gets its own project entry with the hourly rate.

All three sit under the same client in Time-Trak. When you run a client report, you see all activity together. When you filter by project for invoicing, each billing structure is cleanly separated.

This also keeps your historical data clean. If you ever want to look back and understand what you actually earned on the retainer versus the project work, the data is already separated. You do not have to untangle it.

Use Task Categories for Lighter Separation

If the billing difference is at the task level inside a single project, use task categories with different rates instead of separate projects. Time-Trak allows you to set rates at the task category level, so you can have strategy work billed at a senior rate and execution work billed at a lower rate within the same project.

This is useful when the project itself is unified but the work within it has two distinct rates. A single invoice can still pull from both categories correctly because the rates are attached at the category level.

The Flat Fee Project That Still Needs Tracking

Flat fee work is not exempt from this setup. Create the project. Set an internal hourly rate or your target effective rate. Log your hours normally.

The client may never see a breakdown. But you will. At the end of a flat fee engagement, Time-Trak shows you actual hours logged against the project. Divide the flat fee by those hours and you have your effective rate for that engagement.

That number tells you whether flat fee pricing is working for you on this type of project. It also gives you data to price the next similar project with confidence instead of guessing.

Retainer Hours and Overflow Hours Need to Stay Separate

Retainer clients often have a set monthly hours budget. When they go over it, additional work is billed hourly. These two need to be separate projects in Time-Trak.

Log retainer hours against the retainer project. Log overflow hours against the hourly project. When invoice time comes, you can show the client exactly how many hours fell within the retainer and exactly how many were additional, with no ambiguity.

This protects you if a client questions the overflow charge. The data is clean. The hours are logged separately. The conversation is straightforward.

Before You Start the Next Phase, Set Up the Project

Every time a new billing arrangement starts with an existing client, create the project structure first. Do not wait until you have logged ten hours in the wrong place and need to move them.

Three minutes of setup at the start of each engagement keeps your billing clean, your reports accurate, and your invoice conversations short.

Track your time, bill every minute.

Time-Trak is a native Mac and Windows time tracker with a floating timer, automatic screenshots, and one-click invoicing.

Free during beta.

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