A client wants you on retainer. Same fee every month, a set number of hours, first payment on the 1st. Great news. Then the practical question: what does the invoice look like, and do you really have to build it again every month?
This guide covers the retainer invoice from start to finish: what it is, how it differs from a deposit, what to put on it, a complete monthly example with extra hours, how to handle unused hours, and how to set it up as a recurring invoice so it goes out on its own.
Key takeaways
A retainer invoice bills a fixed fee for an agreed period, usually a month, and is normally sent at the start of the period.
Put the period, the scope or hours included, and the due date on every one. Vague line items cause many retainer disputes.
Bill extra hours separately, in arrears, at the rate in your agreement.
Decide in writing what happens to unused hours, and show the hours used on each invoice.
If the amount doesn't change, make it a recurring invoice so you stop rebuilding it every month.
What is a retainer invoice?
A retainer invoice is an invoice for a fixed, recurring fee that a client pays to keep your time, your availability or an agreed amount of work reserved for them. Retainers are usually monthly: a designer covers up to 20 hours of work, a copywriter delivers four articles, a consultant is on call for advice.
The word "retainer" is used in two ways, and it's worth knowing which one your client means:
An ongoing fee (a monthly retainer). The client pays the same amount every period for as long as the agreement runs. This is what freelancers, designers, marketers and consultants usually mean, and it's what this guide is about.
A one-time advance held against future work. The client pays up front and you draw it down as you work, the way many law firms do. Lawyers follow their own trust-account rules for that money, so if you're a lawyer, check your bar's rules rather than a general guide.
Types of monthly retainers
How you word the invoice depends on what the retainer buys:
Hours-based. A block of hours each month, for example "up to 20 hours of design work". A common type, and the one that needs the clearest rules about unused and extra hours.
Deliverables-based. A fixed output, for example "4 blog posts and 1 newsletter per month". You invoice the package, not the time.
Access or advisory. The client pays for priority access to you (calls, quick reviews, advice) rather than a set amount of work.
Not sure how many hours to offer? The billable hours calculator shows how much of your month you can actually sell, which is a good ceiling for a retainer.
Retainer vs deposit vs regular invoice
These three get mixed up all the time. Here's the difference:
Retainer invoice | Deposit invoice | Regular invoice | |
|---|---|---|---|
What it bills | A fixed fee for an ongoing period | Part of one project's total, in advance | Work you've finished |
How often | Every period (often monthly) | Once, at the start of a project | Once per job or milestone |
When you send it | Start of the period | Before work starts | After delivery |
What happens next | The next one goes out next period | Credited against the final invoice | Done once it's paid |
A deposit secures a single project and is subtracted from the final bill. Our guide to charging deposits covers that case. A retainer keeps going until you or the client end the agreement, and nothing is subtracted from a later invoice.
What to put on a retainer invoice
A retainer invoice has everything a normal invoice has (your details, the client's details, a unique invoice number, the invoice date and the due date) plus a few things that matter more here:
The period it covers. "November 2026" or "Nov 1–30, 2026". If the invoice date already shows the period, that can be enough; more on this in the recurring section.
What the retainer includes. The hours, the deliverables or the kind of access. Match the wording of your agreement so the client's accounts team can tick it off.
The fixed fee. One line, one amount. Don't break it into hours × rate unless your agreement does.
Extra work, if any. Hours above the cap on their own line, with the date range and the rate you agreed.
Hours used last period (optional but useful). "October: 23 of 20 hours used" makes overage and rollover easy to check.
Payment terms. Retainers are usually due on receipt or within 7 days. Longer terms like Net 30 mean you could be a month into the work before you're paid for it.
A reference to the agreement. "Per retainer agreement dated Aug 1, 2026" heads off a lot of questions.
Retainer invoice example
Here's a complete monthly retainer invoice for a freelance designer with a 20-hour retainer, billed in advance on November 1. In October the client used 23 hours, so 3 extra hours are billed in arrears on the same invoice. The amounts are an example, not a recommended rate.
Invoice #0047 · Invoice date: Nov 1, 2026 · Due: Nov 8, 2026 (Net 7)
From: Jordan Lee Design · To: Maple Studio (accounts@maplestudio.example)
Description | Qty | Rate | Amount |
|---|---|---|---|
Design retainer, November 2026 (up to 20 hours, per agreement dated Aug 1, 2026) | 1 month | $2,400 | $2,400 |
Additional design hours, October 2026 (23 used of 20 included) | 3 hrs | $120 | $360 |
Total due | $2,760 |
Note on the invoice: "Unused hours don't roll over (agreement §3). Extra hours are billed at $120/hour on the next invoice."
Why this works: the retainer and the overage are on separate lines, each line says which month it's for, the client can see the hours used against the hours included, and the note answers the two questions every client asks.
Want the same layout without starting from scratch? The consulting invoice template and the graphic design invoice template both have room for a retainer line, or you can fill it in the free invoice generator and download a PDF.
When to send it: advance or arrears?
Bill the retainer in advance. Send it at the start of the period, on the same date every month. The client pays for November before you spend November on their work, and both sides know the date it arrives.
Bill extra hours in arrears. You only know the exact overage once the month is over, so add it to the next invoice or send it on its own at the start of the following month.
Pick a fixed day and keep it. The 1st is a common choice. If you start mid-month, either prorate the first invoice or start the cycle on the day you begin and keep that day.
Unused and extra hours
This is where retainer disagreements often start, so settle it in the agreement and repeat it on the invoice. The usual options for unused hours:
Use it or lose it. Unused hours expire at the end of the month. The simplest option, and fair when you're keeping the time free for the client.
Roll over once. Unused hours carry into the next month only, then expire.
Roll over with a cap. Carry over up to a set number of hours, for example 5.
For extra hours, agree on the rate up front (often your normal hourly rate) and whether the client must approve them before you go over. Then bill them on their own line, with dates, so they never look like a surprise.
Set it up as a recurring invoice
If the retainer amount is the same every month, there's no reason to rebuild the invoice every month. A recurring invoice is an invoice your invoicing tool creates and emails for you on a schedule: weekly, monthly, quarterly or yearly.
Note the difference between a recurring invoice and autopay. A recurring invoice asks the client to pay; they still pay each one themselves, by card or bank transfer. Autopay charges a saved card automatically. They solve different problems, and plenty of clients, especially businesses with an accounts payable team, want an invoice anyway.
In Onigiri, recurring invoices are part of the PRO plan. To set one up for a retainer:
Create the invoice with the client, the retainer line and your payment details.
Under Repeat, choose Every month (or every week, every 2 weeks, every 3 months or every year).
Pick the first invoice date and when it ends: never, after a set number of invoices, or on a date. A 12-month retainer could end after 12 invoices.
Check who it's emailed to, add yourself in CC if you want a copy, and write the message once.
Save.
On each date, Onigiri creates the next invoice from this one, with the next invoice number, a fresh invoice date and the same number of days until it's due, emails it to your client at about 9:00 AM your time, and marks it Sent. Your client opens it from the email and pays through the invoice link, by card, Apple Pay or Google Pay. You can pause, change or stop the schedule at any time, and changes apply to future invoices only.
Two tips for recurring retainer invoices:
Leave the month out of the line item. Every new invoice copies the same text, so "Design retainer, November 2026" would say November forever. Write "Monthly design retainer (up to 20 hours, per agreement dated Aug 1, 2026)" and let the invoice date show the period.
Send extra hours as a separate invoice. Keep the recurring invoice to the fixed fee, and send overage as a one-off invoice at the start of the month. Your client's accounts team will find two clean invoices easier to approve than a recurring one you have to edit every month.
If you still want to send the first one by hand with a personal note, the invoice email templates include one for monthly retainers.
Common retainer invoicing mistakes
Billing at the end of the month. That turns a retainer into a month of free credit. Invoice at the start.
Vague line items. "Services – $2,400" invites questions. Say the period and what's included.
Mixing the fee and the overage. One combined amount makes it hard to see what changed. Keep separate lines.
No rule for unused hours. Decide it before the first invoice, not when the client asks for a credit.
Long payment terms. Net 30 on a monthly retainer means you're always a month behind. Due on receipt or Net 7 fits better.
Forgetting the end date. If the agreement runs for 6 or 12 months, set the recurring invoice to end with it.
Consultants have a few billing models of their own on top of retainers; our guide to invoicing as a consultant covers hourly, day rate and milestone billing too.
FAQ
What is a retainer invoice?
A retainer invoice bills a client a fixed amount, usually every month, for your ongoing availability or an agreed amount of work. It's normally sent at the start of the period, before the work is done, and it shows the period, what the retainer covers and the due date.
Is a retainer the same as a deposit?
No. A deposit is a one-time advance on a single project, credited against the final invoice. A retainer is an ongoing fee, billed every period for as long as the agreement runs. Some people also use "retainer" for a one-time advance held against future work, so say which one you mean in your agreement.
Do you invoice a retainer in advance or in arrears?
Usually in advance: freelancers typically invoice the retainer at the start of each period, and bill any extra hours in arrears on the next invoice. That way the client pays for the month before you start it, and overage is billed once you know the exact hours.
What happens to unused retainer hours?
Whatever your agreement says. The common options are that unused hours expire at the end of the month, roll over for one month only, or roll over with a cap. Show the hours used on each invoice so the client sees where they stand.
Can I automate a monthly retainer invoice?
Yes. Many invoicing tools can turn an invoice into a recurring one that is created and emailed on a schedule. In Onigiri this is a PRO feature: pick the frequency and the first date, and each new invoice is emailed to your client with the next number and fresh dates. Your client still pays each one through the invoice link.
Billing a retainer every month? Start Onigiri for free, send your first retainer invoice today, and switch it to recurring on PRO when you're ready. If a payment runs late, the late fee calculator helps you work out the fee.
