ADP runs the payroll and HR software that keeps businesses running. It charges employers a recurring fee to process wages, file taxes, manage benefits, track time, and handle compliance across more than 140 countries. Over 1.1 million businesses use its products, from tiny shops using RUN Powered by ADP to giant corporations running ADP Lyric HCM. Every two weeks, when workers across America get paid, ADP is usually the engine behind that transaction. The company also acts as a co-employer through its PEO business, called ADP TotalSource, where it takes on HR responsibility for over 750,000 workers on behalf of small and mid-sized clients who want big-company benefits without a big HR department. Because employers need to pay people and file taxes no matter what the economy is doing, ADP's revenue tends to hold up even when times get tough. The diagram below traces where the money goes.

Five years of financial data tell a consistent story. Revenue has climbed every single year, from $15.0 billion in fiscal 2021 to $20.6 billion in fiscal 2025. That is steady, predictable growth. Gross margin has also expanded every year, from 42.4% to 46.0%, meaning ADP is keeping more of each dollar it earns. Free cash flow has grown from $2.9 billion to $4.8 billion over the same period. These three trends moving together in the same direction, revenue up, margins up, cash flow up, suggest the business is getting more efficient as it gets bigger.

One number inside that revenue figure is worth understanding separately. ADP collects payroll funds from clients before passing them to tax authorities and employees. While it holds those funds, sometimes for days, it earns interest on them. In fiscal 2025, that interest income from client funds totalled $1.19 billion, up from $1.02 billion in fiscal 2024. That income grows when interest rates are high and when ADP has more clients with larger payrolls. It shrinks when rates fall. It is a meaningful contributor to the company's profitability, and it is tied to conditions outside ADP's control.

Net debt tells a more nuanced story. It was low for most of the five-year period, sitting at just $0.1 billion at the end of fiscal 2024. Then it jumped to $5.4 billion by the end of fiscal 2025. That spike was not a sign of distress. It reflects ADP issuing $1.0 billion in senior notes and taking on short-term borrowings to fund the $1.16 billion acquisition of WorkForce Software in October 2024, plus timing effects from how client funds flow in and out of the balance sheet. ADP returned $3.7 billion to shareholders in fiscal 2025 through dividends and share repurchases, which also used cash. The company still held $3.3 billion in cash at year-end and has $10.6 billion of committed credit lines available.

The risks ADP faces are specific and documented. The company moves more than $3.3 trillion in client funds every year to employees and tax authorities. A single misfiled payment or delayed remittance can result in regulatory fines and lasting damage to client trust. The PEO business adds another layer of exposure: because ADP is a co-employer for over 750,000 worksite employees, it is legally on the hook for wages and benefits even if a client runs into financial trouble and stops sending money. ADP's 10-K filing names this explicitly as a high-severity risk.

Cybersecurity is another documented threat. ADP holds social security numbers, bank account details, and salary information for tens of millions of workers. A successful breach would not just expose data. It could trigger lawsuits, regulatory action, and client departures all at once. On top of that, banking partners who help ADP move money are increasingly classifying the company as higher risk and may reduce or withdraw services. ADP's own filing describes this as a threat to its core operations. Finally, privacy and AI laws are multiplying worldwide. The EU's GDPR, California's CPRA, and new AI-specific rules in multiple jurisdictions all add compliance costs that keep growing.

ADP's AI push, through its ADP Assist tool and its plan to build AI agents for every major HR role, is still early. The company earned real recognition for ADP Assist in 2024 and 2025 industry awards. But the revenue impact of these AI tools has not been separately quantified in the filings. The WorkForce Software acquisition cost $1.16 billion and is being integrated into ADP's global platform. Whether that integration delivers the promised capability for large enterprise clients remains to be seen.