Warren Buffett sat at his desk in Omaha and wrote one line that explained half his fortune. In his shareholder letter, he described float: "money that doesn't belong to us, but that we get to invest." He was talking about insurance premiums, but the same mechanism runs on your payroll cash. The advice you were given told you not to look.

"Outsource your payroll and focus on what you do best." If you have run a business for more than a few years, you have heard this line. It sounds clean. Hand off the tax filings, the direct deposits, the compliance headaches. Let the experts handle it. Stop thinking about it.

That last part is where the advice stops working for you and starts working for someone else.

Payroll float is the gap between the moment you fund a payroll run and the moment your employees get paid. Most processors require you to send the money two to three business days before payday. During that window, the processor holds your cash.

You do not earn interest on it. They do.

ADP's fiscal 2025 annual report, filed with the SEC, shows the scale. The company held an average of $40.4 billion in client funds over the year. It earned $1.36 billion in interest on those funds at an average yield of 3.4 percent. The costs to manage that money are low. Nearly all of that $1.36 billion flows straight to operating income.

That number does not appear on your invoice. You see a processing fee. The float income is a second revenue stream, one that runs on your cash. It is collected without a line item, without a disclosure, and without your consent.

The problem is not outsourcing. Outsourcing payroll is often the right call. The problem is that "forget about it" removes the one behavior that would make the cost visible: paying attention.

ADP's client retention rate sits at 92.1 percent. The average client stays for roughly 13 years. The advice produces the inattention. The inattention protects the revenue stream. This loop is not a bug in the service. It is the business model working as designed.

Most people treat this as a trust problem. It is a system flaw.

The better principle is short: know what your vendor earns from your cash, not just what they charge you.

Once that is clear, three moves follow from it.

Call your processor or log into your admin portal. Find the number of business days between when your account is debited and when your employees are paid. Write it down. If the answer is buried three screens deep in a settings menu, that is a design choice, and it was not made for your benefit. Most operators who have run payroll for a decade have never asked this question, because the advice told them it did not matter.

Request, in writing, your processor's policy on interest earned during the float window. A transparent provider will state whether it retains interest on client funds and under what terms. If the answer is vague or hard to get, that tells you more about the relationship than the fee schedule does.

When you review processors, add one filter. Does the vendor disclose its float practices up front, or bury them? A provider that states its funding lead time and interest policy in plain terms is telling you it can compete on service. One that hides those terms is competing on your inattention.

Running these three moves over the next quarter does something the advice never did:

You see the actual cost of the float window in dollars, not just the fee on the invoice. You see whether your processor treats disclosure as standard or as a threat. You see the gap between what you pay and what the vendor earns from holding your money. And you find out what your cash is worth to someone else during the days you thought it was already spent.

At the end of that quarter, ask three things.

→ How many total days did my cash sit in someone else's account this year?

→ What did the processor earn on my funds that never showed up on my bill?

→ Did any competing provider offer a shorter float window or a different interest policy?

That is the difference between advice that sounds right and a system that proves itself.

Run your own math. A company with $100,000 in biweekly payroll, funding three days early, across 26 pay cycles: about $727 a year in interest you never see. Scale that to $500,000 biweekly, a firm with 100 to 150 employees, and the number is $3,633 a year. The money was already marked as spent in your head. The processor keeps what it earns on cash that still belongs to you.

Buffett called float "money that doesn't belong to us." He was right. He built a $176 billion position on the principle. Your payroll processor runs the same play on a smaller stage, using your money as the raw material. You were told not to notice. Now you have the number. That is not a reason to be angry. It is a reason to read your next invoice differently.