How much can we afford to pay to book a job?
Start with the gross profit a typical job of that type leaves after labor, materials and direct costs. Decide what share of that profit you are willing to hand to marketing. That share is your ceiling for cost per booked job. Spend above it buys revenue that does not pay for itself. The ceiling is different for every job type, and it moves with your capacity and the season.
Work backwards from gross profit, not revenue
Percent-of-revenue rules are the most common way operators get this wrong. Two jobs with identical revenue can leave very different profit once technician time, materials and subcontracted work are removed. Marketing has to be paid out of what is left, so the ceiling has to be derived from margin.
The derivation is simple: gross profit per job of that type, multiplied by the share of profit you are willing to spend to acquire it. What is left is your target. Job costing accuracy determines whether the answer is real, which is why this work usually starts inside the operational data rather than in a spreadsheet.
The ceiling changes when your schedule does
When trucks are idle, the relevant cost of taking one more job is close to variable cost only — the technician is already on payroll. When you are booked out and turning work away, the cost of an incremental job includes the better job you displaced. The affordable ceiling is genuinely higher in the first case and lower in the second.
Most operators run a fixed target year-round and then wonder why marketing feels wasteful in peak season and starved in the shoulder months. Tying the ceiling to capacity is one of the few adjustments that improves both revenue and cost at the same time.
Repeat value raises the ceiling only if you can prove it
It is legitimate to spend more to acquire a customer who will come back — if your own history shows they come back. Pull the retention curve from your system rather than assuming an industry figure, and use observed repeat gross profit, not projected. Then raise the ceiling by what you have actually observed and no more.
Borrowing against unproven retention is how marketing budgets quietly outrun cash. Retention data should set that adjustment, not optimism.
One ceiling per job type, published
Write the ceilings down and put them on the same report as actual cost per booked job. The moment a channel's marginal cost crosses its ceiling, the conversation about whether to keep funding it becomes a two-second decision instead of a meeting.
Expect the ceilings to be uncomfortable the first time you calculate them. Most operators discover at least one channel they have been funding above what the work can support, and at least one they have been starving well below it.
Topics: contribution margin · budget · unit economics · job types
Have a version of this question about your own business?
The useful answer usually depends on which systems you run and how they're connected. That's a conversation, not a blog post.