Buying media through an intermediary is normal and often unavoidable, because scale and relationships get better rates than a single advertiser can. The part that is not obvious from a proposal is whether the firm is spending your money on your behalf, with the costs disclosed, or buying inventory itself and reselling it to you at a price of its choosing. Both models are lawful and common. Only one of them lets you ever know what the media cost.
Agent and principal, and why it matters
As your agent, the firm places buys in your name, discloses what was paid, and charges a fee. As a principal, it buys inventory on its own account and sells it to you as a package, so the difference between the two prices is its margin and is invisible by design. Ask which applies to every line of the plan, in writing, because a single engagement often mixes both without saying so.
Rebates, incentives and what is passed back
Volume agreements between media owners and buying groups can return value to the buyer after the fact. Your contract should say whether any such value attributable to your spend is passed to you, credited, or retained. This is not an accusation; it is a term. A firm that will state its policy plainly is easy to work with, and one that treats the question as impertinent has answered it.
Ask for the right to audit, and use it
An audit clause allowing an independent party to inspect the records relating to your buys is the only reliable check on any of the above. It is more effective as a deterrent than as an exercise, and it costs nothing to include at signature. Also agree the format of the backup documentation you receive each month, so that an audit would have something to work from.
Verification is a separate purchase
Whether an impression was viewable, served next to acceptable content, and delivered to a human is measured by third parties, not by the seller or the buyer. Decide who pays for verification and who receives the reports. An agency that is relaxed about independent verification of the inventory it recommends is asking you to take its word on the one thing that is genuinely checkable.
Questions people ask about ad buying agency
Is principal-based buying always bad for the advertiser?
Not necessarily; it can deliver genuinely cheap inventory bought at scale, and for some formats it is the only practical route. The problem is not the model but undisclosed use of it, because you cannot judge value when the cost is hidden and the fee looks like zero.
How are ad buying agencies usually paid?
A commission on spend, a flat retainer, a fee per campaign, or margin on resold inventory. Ask for the same plan priced on a disclosed fee basis and compare it against the packaged price; the gap is the information you were missing.
Do we need an ad buying agency for digital only?
For self-serve platforms you can buy directly, and many advertisers do while paying for expertise rather than access. Buying agencies earn their place where the inventory is negotiated rather than auctioned, such as broadcast, out-of-home, print and large programmatic guaranteed deals.
What should the monthly reporting contain?
Spend by placement against plan, delivery against what was booked, verification metrics, and a reconciliation to the invoices. If the report cannot be tied to invoices without help, it is a presentation rather than an account of what happened to your money.