A retainer is the holy grail of freelancing. Instead of hunting for new clients every month, you secure a predictable, recurring income stream. But billing for a retainer requires a different approach than billing for a one-off project. This guide will show you exactly how to structure, track, and invoice retainer agreements.
What Is a Retainer?
A retainer is a recurring agreement where a client pays you a set fee every month (or quarter) to guarantee your availability or to deliver a specific set of recurring services. For freelancers, retainers provide financial stability. For clients, they guarantee priority access to your skills without having to negotiate a new contract for every small task.
The Two Types of Retainers
Before you can invoice for a retainer, you need to know which type of retainer you are offering.
1. Pay-for-Work (Deliverable-Based Retainer): The client pays a flat monthly fee for a specific output. For example, a freelance writer might charge $2,000/month for four 1,500-word blog posts.
2. Pay-for-Access (Time-Based Retainer): The client buys a block of your time. For example, a freelance developer might charge $3,000/month to reserve 40 hours of development time.
Time-based retainers require meticulous time tracking. Deliverable-based retainers are easier to manage but require strict boundaries to prevent scope creep.
When Should You Send a Retainer Invoice?
Always bill in advance. A retainer is a reservation of your capacity. Just like paying rent on an apartment, the client pays on the 1st of the month for the right to use your services during that month.
Set up your invoicing software to automatically generate and send the retainer invoice on the 25th of the preceding month, with a due date of the 1st. If payment is not received by the 3rd or 5th, pause all work. Do not do a month's worth of work on the promise that the retainer will be paid later.
How to Write the Invoice
A retainer invoice should be clean and explicit about what billing period it covers.
- Invoice Date: The date it is generated (e.g., May 25).
- Due Date: The start of the service period (e.g., June 1).
- Line Item Description: Be specific. Instead of writing "Retainer," write "Monthly Retainer: June 2026 (Includes up to 20 hours of Graphic Design support)."
- Terms: Note whether hours roll over. For example: "Unused hours expire on the last day of the month."
Handling Overages and Unused Time
Unused Time: Do not let hours roll over indefinitely. A "use it or lose it" policy is standard. If hours roll over, a client might use zero hours for three months, then demand 120 hours of work in month four, completely destroying your schedule.
Overages: If a client buys a 20-hour retainer and requests 25 hours of work, you must bill for the extra 5 hours. Do not put this on the next month's retainer invoice. Send a separate invoice at the end of the month labeled "Retainer Overage: June 2026." Alternatively, pause work at hour 20 and ask the client if they want to authorize overage billing.
Retainer Invoice Templates
You don't need a complex Word document to create a retainer invoice. Use a standard invoice layout but modify the line items.
If you are negotiating a new retainer and want to figure out exactly how much to charge based on your target annual income and available capacity, use our Retainer Calculator to run the numbers before you send the proposal.