Definition
Retainers are common in professional services — agencies, consultants, lawyers, accountants. The buyer pays a fixed monthly fee in exchange for a defined scope of work or a guaranteed allocation of the supplier's time. Retainers are usually billed in advance on the first day of the period.
Two common models: scope-based (a defined deliverable each month, e.g. 'one report and four meetings') and capacity-based (a number of hours each month, used however the buyer chooses). Each has different drift risks and should be priced differently.
Why it matters
Retainers can stabilise a service business's cashflow dramatically — they convert lumpy project income into predictable monthly revenue. They also create unhealthy patterns if scope is not tightly defined: both sides drift, the buyer expects more than they pay for, and the relationship sours when one side feels the deal has tilted.
Where this appears in your tools
The Proposal Builder supports retainer pricing as a model alongside fixed-fee and hourly. The payment terms example page shows a sample retainer terms block.
Example
An agency retains a client at 4,000/month for 'up to 30 hours of work, including a monthly strategy meeting.' Three months in, the client is consistently asking for 45+ hours. Without a written cap and a change-control clause, the agency is delivering 50 percent more work for the same fee.
Common confusion
A retainer is not a discount. Some buyers expect a lower hourly equivalent in exchange for the commitment; the trade-off is actually capacity certainty for the supplier, not always a discount on rate.