Retainers: How to Invoice Monthly
A retainer is a reserved block of your time. Learning how to invoice monthly retainers keeps that arrangement boring, which is what both sides want. This guide covers when to send the bill, how to describe included hours and how to handle extras without rewriting the whole agreement each month.
Invoice the Period, Not a Mystery Fee
Write a line such as "July content retainer, 12 hours included" or "Monthly bookkeeping support, August". Add the date range. If unused hours roll over or expire, say so in the notes. Clients should never have to guess whether they are prepaying or paying for last month.
Pick a calendar day and reuse it. The first working day of the month is a common choice for retainers billed in advance. Recurring work also pairs well with the ideas in recurring invoices.
A clean monthly retainer invoice
- Invoice number in sequence with your other work.
- One retainer line with the month and included hours or scope.
- Extra hours or projects as separate lines.
- The same payment details every time.
Extras and Overages
When the client uses more than the bundle, invoice the extra hours on their own line after they agree. Do not silently raise the retainer. If they want a permanent increase, change the retainer on the next month's invoice and confirm it in writing first.
Industry examples for consultants and VAs are in consulting invoices and VA invoices.
Good to know: You can build each month's PDF in our free invoice generator from a browser draft. Change the month, keep everything else.
Track Hours Off the Invoice
Keep a simple hour log for yourself. The invoice stays readable; the log answers "what did we use?" if the client asks. That split is the same idea as attaching a timesheet only when needed.
Monthly retainers work when the invoice is predictable and the extras are visible.
Watch out: Unused hours, refunds and cancellation notice belong in the contract. The invoice should follow that contract, not invent new rules.
Frequently Asked Questions
Do I invoice retainers in advance or in arrears?
Either can work. Advance billing helps cash flow. Arrears billing matches hours already used. State the choice in the agreement.
Should every month get a new invoice number?
Yes. Never reuse a number, even for the same client. See invoice numbering.
What if the client pauses for a month?
Skip that month or invoice a pause fee only if the contract allows it. Do not send a silent full retainer.
Bill this month clearly. Create a free retainer invoice.