How to invoice retainer clients

Invoice retainer clients in advance: send the invoice on the 1st of the month for the month ahead, or on signing for the first period, with net 7 to net 15 terms. Follow it at month end with a usage statement that shows hours delivered by department against the cap, and bill overages, hourly work and pass-through costs on separate lines from the retainer fee.

This guide uses a $15,000 monthly retainer split across SEO, content, social and PR for a 12-person agency. The structure applies to any drawdown retainer regardless of size. If the retainer is not yet priced by department, start with how to price agency retainers.

Why bill retainers in advance?

A retainer reserves capacity. The agency has scheduled the team for the month and will pay them whether or not the client uses the hours. Billing in advance matches the cash to that commitment and puts the client in the position of having paid for what they are about to receive, rather than owing for what they already got.

Invoice on the 1st for the month ahead. For a new client, invoice on signing for the first period and align subsequent invoices to the 1st, prorating the first month if the start date is mid-month. Work begins when the first invoice is paid, and saying so in the contract removes the awkwardness of enforcing it later.

What should the retainer invoice contain?

The invoice is a document the client's accounts payable team will process without context. It needs to be self-explanatory, match the contract wording, and separate the retainer fee from anything that is not the retainer fee.

A sample invoice for the example retainer, with one approved overage from the previous month and a media pass-through, looks like this.

What goes in the monthly usage statement?

The usage statement is sent at month end and shows what the retainer bought. It is not an invoice. It shows hours by department against the cap, the remaining balance, any approved overages and the servicing gap, and it is the document that makes repricing at renewal an arithmetic exercise rather than a negotiation.

Two things stand out in this statement. Social delivered 2 hours over cap without an approved overage, which is $250 of unpaid work and a conversation for the account manager before it becomes a pattern. PR is 4 hours under, and if that repeats for three months the PR allocation should drop at renewal.

Send the statement within three business days of month end, attached to the next invoice or on its own. Clients who receive a statement every month rarely dispute the renewal price, because they have watched the numbers move. Verbial generates the statement from logged time and the retainer's department caps, so it matches the invoice without a spreadsheet in between.

How do you invoice pre-paid overages?

An overage is work above the department cap. The rule is approve, invoice, pay, then work. The account manager quotes the additional hours at the department rate, the client approves in writing, the agency issues an overage invoice with short terms, and the work starts when payment clears.

Once paid, the cap for that department rises by the approved hours for the current period only. On the next 1st, the cap resets to the contracted allocation. An overage never becomes a permanent increase without a contract amendment.

How is hourly work billed?

Hourly work outside the retainer is billed in arrears from approved time, at the rate card, on the next monthly invoice. Approved means a manager reviewed the entries before they reached the invoice. Unreviewed time on an invoice is the fastest route to a dispute, because a 15-minute entry labelled "misc" is not something AP will pay without a question.

Hourly lines carry the hours, the rate, the period and a short description that matches the approval. Decide before the work whether it draws down the retainer or is billed separately. Group them by project rather than by day. Attach the time detail as a separate document rather than putting 40 entries on the invoice itself.

How do you handle pass-through costs?

Pass-through costs are money the agency spends on the client's behalf: media spend, stock licenses, software seats, print. They are not agency revenue and should never be blended into the retainer fee. Invoice them at cost or with a markup the client agreed to in writing, on a separate line or a separate invoice.

Separate treatment keeps the margin readable, since a $15,000 retainer that includes $6,400 of media spend has a very different gross margin from one that does not. It also matters for revenue recognition: pass-through amounts are typically not recognized as revenue, and card processing fees on a $6,400 media pass-through are $190 the agency will never recover unless the line is billed by bank transfer.

What payment terms should you use?

Net 7 to net 15 for retainers. Net 30 is the default on most accounting templates and it is the wrong default for advance-billed retainers, because the invoice sent on the 1st is paid on the 31st, at which point the agency has covered the month's payroll from cash and is about to invoice the next one.

At 10 retainer clients on net 30, the agency is permanently floating $150,000 of receivables. Moving them to net 10 releases roughly $100,000 of working capital once, and that is usually worth more than any discount the client asks for in return.

Which payment methods should you accept?

Accept the method that gets paid fastest, and make it the default. Card on file with automatic charging on the due date removes the dunning problem for most small and mid-sized clients. Bank transfer suits larger invoices where card fees of 2.9% on $15,000 add up to $435 a month.

Stablecoins are relevant for agencies with clients outside their banking corridor, where a wire takes five days and costs $45 each way. Verbial accepts card, bank transfer and USDC/USDT on invoices. Whatever the method, state it on the invoice with the details needed to pay, and do not make the client ask.

What should the dunning schedule be?

Dunning is the sequence of reminders and consequences for an unpaid invoice. Write it once, state it in the contract, and run it the same way for every client. The schedule below assumes net 7 terms and an invoice sent on day 0.

Pausing means no new work starts. Work in progress is finished to a safe stopping point and held. Deliverables are released when payment clears. Most invoices open at day 8 are an AP process issue, and the day 3 reminder with a payment link resolves most of them.

How do you handle disputes?

A dispute is a client saying an invoice is wrong, and the response is to look at the evidence before defending the number. Pull the usage statement, the approved time entries and the overage approvals for the period. If the invoice matches those documents, send them. If it does not, correct the invoice the same day and say so.

Disputed lines should not hold up undisputed ones. Ask the client to pay the undisputed balance on the original terms and hold the disputed amount while it is resolved. Issue a credit note rather than editing a sent invoice, so the records on both sides stay consistent.

Start free with Verbial at /signup to bill retainers in advance and send usage statements from logged time.