A retainer looks like the most comfortable kind of client work: a predictable monthly fee, a steady flow of videos, no pitching every few weeks.
It is also one of the easiest places for a studio to lose money without noticing, and for a client to feel short-changed without saying so. Most of the problems come from terms that were never quite pinned down.
This is how I'd set one up so both sides can see exactly where they stand.
Define the unit as a video, not hours
Clients buy outcomes. A retainer written in hours invites arguments about how long things should have taken, and it makes your efficiency your problem: the faster your editors get, the less you earn.
Define the allowance as a number of videos a month. Then define what a video is — its length range, the rounds included, and the deliverables that come with it, such as cut-downs or extra aspect ratios.
A clear unit makes every other part of the retainer easier to agree.
Cap the rollover
Clients have quiet months. If unused videos vanish at month-end, the client feels they paid for nothing.
If they roll forward indefinitely, you can end up owing a backlog that lands all at once and swamps your schedule. The middle ground is rollover with a cap: unused work carries forward, but only up to a set amount.
Put the cap in writing. Show the client their rolled-over balance every month, so it never comes as a surprise.
Bill overage separately and visibly
When a client goes past their allowance plus rollover, the extra work is overage. Charge for it at a rate agreed in advance, on its own line, not folded into the monthly fee.
Tell the client when they are getting close to the limit, not after the invoice arrives. Overage that is visible and expected feels fair; overage that appears without warning feels like a penalty, even when the terms allowed it.
Keep credits against the client, not in your head
Refunds, overpayments, goodwill gestures, a video you agreed to redo at no charge — these are all credits. They have a habit of being remembered by one side only.
Record each credit against the client the moment it is agreed, with a short note of why, and apply it to the next invoice. A credit that lives in someone's memory gets forgotten or argued about, and either outcome costs you trust.
Bill in arrears on delivered work
Invoice for what was delivered in the month just ended, not for what you expect to deliver next. That way the invoice matches reality.
It can show the allowance, what was used, what rolled over and any overage, all from work that has actually shipped. If your terms put the base fee in advance, keep it there — it's the variable parts that belong in arrears.
Keep drafts open long enough
Draft the month's invoice when the month closes, but don't send it straight away. Leave it open for a short, agreed window.
That gives late adjustments time to land — a disputed overage, a credit agreed on the last day, a delivery that slipped across month-end. Correcting a draft takes a minute; correcting an invoice the client has seen means a credit note and an awkward explanation.
Put it all on one page
Everything above is easier when the client can see it. A short monthly summary — allowance, rolled over, used, overage, credits applied — answers most retainer questions before they are asked.
When both sides are looking at the same numbers, nobody feels cheated. The conversation can stay about the work.