How to tell if your agency

An agency’s cost to you is more than the fee in the contract. Ten years after its landmark investigation into agency rebates, the Association of National Advertisers (ANA) surveyed advertisers again in 2026: 43% still have concerns about transparency with their media agencies. Only 54% said their contracts specifically address rebates, and 61% address principal media.

Why the invoice doesn’t tell the whole story

Agencies have spent years under pressure to lower fees while delivering more. To protect their margins, many make up the difference in places most clients never look: in staffing, in media and technology costs, and in payments that never appear on your invoice. None of these is automatically wrong. The problem is not knowing they exist, or what they cost.

Principal media shows how quickly this is changing. In a principal buy, the agency buys media itself and resells it to you, often with a margin you can’t see. In the ANA’s March 2026 study, 58% of marketers said their companies had used principal media in the past year, up from 47% in 2024.

Why it matters at any budget size

Large advertisers have procurement teams and media auditors. Most growing businesses don’t, so the same blind spots can go unchecked for years. A smaller budget has less room for money that isn’t working.

An independent review doesn’t assume bad intent. Most of these costs can be found by asking the right questions and reading the contract closely. The goal isn’t to replace your agency, but to make sure you know what you’re paying for.

Seven costs that don’t appear on the invoice

1. More junior teams

Senior people win the business, and less experienced people do the work. You can end up paying senior rates for time your account never gets.

2. Partial or unfilled roles

You pay for full-time team members, but roles sit open during turnover or people are split across other clients. Hours reports are self-reported and rarely verified.

3. Tech and data fees

Platform, data and measurement charges layered into media buys, often folded into a single rate instead of being itemized.

4. Principal media

Media the agency owns or buys in bulk, then resells to you at a markup, whether or not it is the best fit for your plan.

5. Rebates and volume bonuses

Payments from media owners back to the agency, based on how much is spent with them. Your contract should say whether they are passed back to you.

6. Commissions on specialty spend

Influencer and other channels billed through the agency with a commission added. The ANA’s February 2026 study found agencies receive about 30% of influencer marketing spend on average.

7. Fee fragmentation

Small separate charges for setup, reporting, tools or production that add up well past the headline fee. They are visible, but scattered across invoices.

Ask before you assume

Most questions about agency costs have clear answers, and a good partner will welcome them. If the answers are vague, slow or missing, that tells you something too. We would start with the contract: audit rights, disclosure of rebates and principal media, and fees reported separately from the cost of media.

Questions to ask your agency

• Do you receive rebates, incentives or other payments from media sellers, and are they passed back to us?

• Are you buying media as our agent, or reselling it to us at a markup?

• Can we see media costs and agency fees separately, by channel?

• Who on our account is senior, how much of their time do we get, and are any roles open?