Your Client Can Defend Their Ad Spend. Can You Defend Your Agency's?

By Craig S. Cody, CPA, Certified Tax Coach. Published August 1, 2026.

Here's the answer up front. Public company CEOs have started defending their media spending out loud on earnings calls, so the standard of proof your clients live under just went up. Most agencies will meet it by building a better client dashboard. That's the second job. The first one is harder and nobody assigns it: run the same test on your own agency. Can you state your agency gross income, your people cost against it, and your weeks of cash, right now, without opening a spreadsheet? If you can't produce your own numbers on demand, you're in no position to coach anyone else's finance team on theirs.

I've been a CPA firm owner for 23 years, and our firm works with more than 70 agencies every month. So I've had this moment across the desk more times than I can count. An owner walks me through a client's performance to two decimal places, cost per lead, blended CAC, incrementality, the whole thing. Beautiful work. Then I ask what his own gross profit was by service line last quarter, and he tells me he'd have to ask his bookkeeper. He can defend somebody else's dollars better than his own. That's the gap I want to close.

What Just Changed, and Why It Lands on You

Marketing effectiveness stopped being a fight between the CMO and the CFO. It became something CEOs brag about.

Digiday's Sam Bradley reported on July 31 that several big brand bosses used second-quarter earnings calls to talk not just about spending advertising money, but about spending it well. Starbucks' CEO praised his CMO's handling of a $190 million budget. Kraft Heinz told analysts its global return on ad spend rose 8% after consolidating to fewer media partners. CEOs usually give advertising a sizzle reel and one line about the summer campaign, so that's a real shift.

Meanwhile, Gain Theory's Global CMO Survey found that 49% of senior marketing leaders lack the data to defend creative investment to their CFO. Be careful with that one, because it gets quoted loosely: 115 senior marketers at global brands, and it's about creative specifically. The companion stat matters more to you anyway. About one in four of them had budgets cut because they couldn't show the spending was working.

Read that as an agency owner, not as a marketer. Their budget is your revenue. When a client's budget gets cut for reasons that have nothing to do with the quality of your work, you lose the retainer anyway.

Could Your Agency Pass the Test You're About to Give Your Client?

This is the question I actually care about, and it's the one the headlines hide.

Try it. Right now, without opening anything, say out loud what your agency gross income was last month. Not billings. AGI, what's left after the pass-through money that was never yours: media, freelancers, production, printing, client software. Then say what percentage of that went to people. Then say how many weeks of operating cash you're sitting on.

If those came out in ten seconds, good. You're in a small group and the rest of this is a tune-up. If you reached for a spreadsheet, or caught yourself reaching for billings because it's the number you say to other owners at conferences, that's the finding.

The agencies I work with that flourish aren't smarter than the ones that struggle. They just know their own numbers with the same discipline they bring to a client's campaign. And there's a credibility problem underneath this that owners underestimate: if you're about to sell a client's CFO on rigorous measurement of their marketing money, and your own management reporting is a cash-basis P&L you glance at in April, you're selling something you don't practice.

Which Five Numbers Do You Have to Be Able to Defend?

Five. If you can state these cold, you can hold your own in any finance conversation, starting with the one about your own business.

1. AGI, your agency gross income. Billings minus the pass-through costs. Quick note for anyone who's been in a tax conversation with me: this is not the Adjusted Gross Income on your 1040. The collision is real, so I name it every time. AGI is the money that's actually yours to run on, and it's what you should run the agency by instead of revenue.
2. People cost as a percentage of AGI. At or under 55%. That benchmark isn't mine. It comes from Drew McLellan and the Agency Management Institute, whose 55/25/20 model splits AGI into roughly 55% payroll, 25% overhead and 20% profit. It matches what I see in the P&Ls. Above 55% you're usually funding payroll creep instead of profit.
3. AGI per full-time employee. The productivity number, and the bar has been moving up as AI absorbs production work. I've written about why this is the real measure of your AI return rather than "the team is faster."
4. Net profit as a percentage of AGI. AMI's model targets 20%. Agencies that genuinely run to the metrics tend to land nearer 17%, against an industry average that runs under 10%. Knowing which side of that you're on is the point.
5. Weeks of operating cash. Because a beautiful P&L can still bankrupt you. Profit isn't cash, and the gap between doing the work, billing it and collecting it is where agencies get hurt.

Notice what's not on that list: revenue. Revenue is the number you say at conferences. It's an ego number inflated by other people's money passing through your account.

Two of the five carry more weight than the rest, and they're the two owners skip. People cost against AGI tells you whether the business model works. Weeks of cash tells you whether you'll still be here to fix it if it doesn't.

What Do the Three Layers Look Like on Your Own P&L?

Any defensible report has three layers, in order: activity (what we did), outcome (what changed), economics (what it was worth). Almost every agency report stops at the first one, and the first one is worth the least to a finance reader.

Point them at your own agency and they get useful fast.

Most owners live entirely in the top-left cell. They can tell you utilization to the hour and can't tell you which service line actually makes money. That's the same failure they're about to criticize a client's marketing team for, and it's usually not a discipline problem. Nobody ever handed these humans the bottom row.

How Sure Are You? Label Every Number

Here's the part that separates a report people trust from one they quietly discount. Start by doing it to yourself.

Take your own five numbers and sort them into three tiers:

• Measured. You can tie it to a transaction or a record. Cash in the bank.
• Inferred. It moves with the work in a way that's consistent and testable, but other things moved too.
• Assumed. You believe it, and you can't show it.

Be ready to be annoyed. Your AGI is measured. Your utilization is probably inferred, because it depends on humans logging their time honestly. Your margin by service line, if your books are cash basis and your retainers bill ahead of the work, may be closer to assumed than you'd like. That sort tells you exactly which part of your monthly close to fix first, which is worth more than any dashboard you could buy.

Then do the same on the client report and say which is which, out loud, in the document. It feels like weakening your own case. It does the opposite. A CFO deals with estimates all day. What they don't deal with well is somebody who won't tell them which numbers are soft, so they discount all of them equally and your best evidence gets marked down to the level of your weakest.

What About the Client Report?

Once you can do this for yourself, the client version is straightforward. Replace the monthly activity report with a one-page decision memo: the spend and the period, the three layers with economics on top, the confidence line, and the decision you're recommending.

That last part matters more than the formatting. A report without a recommendation is homework you handed to your client. The one that survives a budget review isn't the prettiest one. It's the one that ends with a decision the reader can approve.

Who Is This Not For?

If you're a small shop billing project work to owner-operators, there's no CFO in your client's building and there isn't going to be one. The five numbers still run your agency. Just don't rebuild client reporting for an audience that doesn't exist.

And if your books are cash basis with no monthly close, don't start with the client dashboard. Start with the close. You can't report economics you don't compute, on your own P&L or anybody else's.

Frequently Asked Questions

What's the difference between AGI and revenue for an agency?
Revenue, or billings, includes pass-through money like media buys, freelancers and production that flows out to vendors. AGI, agency gross income, is what's left after those costs, and it's the money that actually supports the agency. Note that agency AGI is a different thing from the Adjusted Gross Income line on a personal tax return.

Which numbers should an agency owner know without looking them up?
Five: AGI, people cost as a percentage of AGI, AGI per full-time employee, net profit as a percentage of AGI, and weeks of operating cash. Revenue is not one of them.

What percentage of AGI should go to payroll?
Roughly 55% or less. That figure comes from Drew McLellan and the Agency Management Institute, whose 55/25/20 model splits AGI into about 55% payroll, 25% overhead and 20% profit. Above 55% you're usually funding payroll creep rather than profit.

What if my own books can't produce these numbers?
Then that's the first project, and it's a bigger deal than any reporting template. You need a monthly close, accrual-basis management reporting, and AGI tracked separately from billings.

How do I prove marketing ROI to a client's CFO?
Lead with the economics layer, state a confidence level on every number, and end with a decision rather than a summary. Labeling a number as inferred feels like weakening your case, but an unlabeled report gets discounted uniformly, which drags your solid numbers down to the level of your soft ones.

Start With Your Own Ledger

Your competitors will spend this year building a better client dashboard. Worth doing, and it's a deliverable anyone can copy. Getting your own five numbers in order is the part that isn't, because it means that when you sit across from a client's finance team and talk about disciplined spending, you're describing how you actually run your own business.

Nobody's looking out for your money but you. We work with agency owners every month on exactly this: the monthly close, the margin by service line, and the tax planning that turns a good year into money you keep instead of money you send in. If you couldn't answer those three questions in ten seconds, let's talk.

Craig S. Cody, CPA | Agency CPA | craigcodyandcompany.com

Craig S. Cody is a CPA, Certified Tax Coach, and former NYPD Lieutenant who helps agency owners keep more of what they make through proactive, year-round tax planning and fractional CFO work. This article is general business and tax education, not individualized tax, legal, or financial advice. The 55/25/20 benchmark and the profitability figures cited here come from Drew McLellan and the Agency Management Institute, not from this firm. Work with your own advisor on your specific situation.