How to bill a monthly retainer

Retainers smooth out freelance income, but only if the billing is boring and predictable. The pricing guide explains when a retainer makes sense; this post, part of our getting paid series, is about the invoice itself. To set the monthly price, use the retainer calculator.

Three retainer models

When to send the invoice

Bill in advance, on the same date each month (the 1st or the date the retainer started), due on receipt or within 7 days. Billing at the end of the month for time already worked turns a retainer into ordinary hourly billing with extra risk. The exception is overage: hours beyond the bank are billed in arrears, on the next month's invoice, once you know the number.

Sample retainer invoice

INVOICE 2026-041
From: [Your business], [address], [email]
To: [Client legal name], Attn: Accounts payable, [address]
Invoice date: April 1, 2026 · Due: on receipt (April 1, 2026)

April 2026 retainer, up to 20 hours of [design and development]: $2,000.00
March 2026 overage: 2 hours at $110.00 (log attached): $220.00

Total due: $2,220.00

Hours bank: March used 26 of 24 available (20 + 4 rolled from February). April starts with 20 hours; no rollover from March.
Pay by card at the link above or by ACH to [account details].
Terms: retainer agreement dated [January 15, 2026].

A clause for unused hours

HOURS. The monthly retainer covers up to [20] hours of work in that calendar month. Up to [5] unused hours roll over to the following month only and are used before that month's hours; rolled-over hours expire at the end of that month and are not refunded. Hours beyond the available total are billed at $[110] per hour on the next monthly invoice. Contractor will tell Client when [80]% of the month's hours are used.

Tracking hours against the bank

1. Create one project per retainer client so every entry lands in the same place.
2. Track time as you work, not from memory on the 30th.
3. Check the total every Friday and email the client when they pass 80% of the month's hours.
4. On the 1st, run a report for the previous month: hours used, rollover, overage.
5. Attach the report (or a summary) to the new retainer invoice.

Billing access and deliverables retainers

An access retainer has no hours to count, so the invoice should name what the client gets: response time, a standing call, a number of requests. Keep a short log of requests anyway; it's your evidence when you raise the price. A deliverables retainer bills for output, so list each deliverable for the month on the invoice and say what happens to one the client didn't request in time: delivered next month, or forfeited. Either way, send the invoice before the month starts and don't let "we'll pay when it's done" creep in.

Ending or pausing a retainer

Put a notice period in the agreement, commonly 30 days, so neither side can end the arrangement the day after an invoice is paid. If a client wants to pause for a month, treat it as a written change: no invoice that month, and rolled-over hours either expire or carry over by the rule you agreed. At the end, send a final summary of hours used and any overage, and invoice the overage on its own.

Taxes on retainers paid in advance

Under the cash method most freelancers use, a retainer is income when you receive it (IRS Publication 538), so a December retainer for January work counts in December. If you use the accrual method, advance payments follow different rules; ask your accountant.

In SoloWOS

In Invoicing, set the retainer invoice to repeat every month on the 1st: on each date SoloWOS creates the next one with a new number and emails it to the client with the pay link. It doesn't charge a saved card; the client pays each invoice. Time Tracking holds the hours: track against the client's project, mark entries billable, and run the report by project and date range (with CSV export) to see the bank. For overage, "Add unbilled time" turns the project's billable entries into lines on a separate invoice, since the recurring one copies the same lines each month. Solo includes 50 invoices a month, recurring ones included, and optional reminders chase a retainer invoice that goes unpaid.