Do you load campaign cost into the deal or keep it as overhead?

I closed the books on a quarter of sourcing spend and realized my cost per contract changes the deal answer depending on where I put it.

Say a campaign runs 3,400 in data and postage over eight weeks and produces one contract that assigns for 9k. If I charge the whole 3,400 to that deal, it made 5,600 and my minimum acceptable spread just moved up. If I treat sourcing as monthly overhead, the deal made 9k and the 3,400 sits in a marketing line I judge once a year.

Both are defensible. The per-deal version keeps me honest about whether thin assignments are worth the calendar time, and it kills marginal deals early. The overhead version matches how the spend actually behaves, because a list keeps producing for months and a contract in March can come off January mail.

Where each one bites. If you load per deal, you will talk yourself out of a 6k assignment that was close to free money on a list already paid for. If you run it as overhead, you can go a year with a healthy looking deal log and a shrinking bank balance, because nothing in the deal math ever objected.

I've been using a trailing twelve month cost per contract as the load, which is a compromise that hides a lot inside an average (my averages have been ugly). Interested in how people doing real volume treat it.