ADP suits businesses that want a provider they can grow with from a handful of staff to thousands, because it sells separate products by company size, from RUN Powered by ADP for 1-49 employees to enterprise HR. Paychex suits small and mid-sized businesses that want payroll and HR from one provider with clear plan tiers, from Basic to Complete. Both calculate, file and pay payroll taxes and offer a PEO, so compare the plan that matches your headcount.
These are the two biggest names in US payroll, and both now sell far more than paycheques: HR, benefits, time tracking, compliance and PEO services. I read ADP's small business and home pages and Paychex's small business payroll and home pages.
ADP and Paychex side by side
| ADP | Paychex | |
|---|---|---|
| Small business product | RUN Powered by ADP (1-49 employees) | Basic, Foundations, Advanced and Complete plans |
| Larger businesses | Separate products for 50-999 and 1,000+ | Advanced and Complete plans |
| Payroll taxes | Payroll tax compliance services | Calculate, pay and file payroll taxes automatically |
| PEO | ADP TotalSource | Paychex PEO |
| Extras | Online store of HR apps, benefits, compliance | Recruiting, time and attendance, 401(k), insurance |
| Track record | Over 70 years | ~840,000 clients, 50 years |
The size bands that decide which ADP you get
ADP doesn't sell one product to everyone. Its site splits customers into businesses with 1-49 employees, 50-999 employees and 1,000+ employees, with RUN Powered by ADP for the smallest group and other platforms above it. That matters if you're near 50 staff: ask which product you'll be on, and what moving between products involves as you grow.
How Paychex lays out its plans
Paychex lists four plans for small business payroll: Basic for essential payroll and HR, Foundations for payroll, reporting and HR, Advanced with hands-on support, and Complete, a full suite of HR, payroll, workforce and talent tools. It says you can run payroll in as few as two clicks, that it calculates, pays and files payroll taxes automatically, and that employees get self-service. It describes itself as trusted by about 840,000 clients.
PEO or payroll only?
Both offer a professional employer organisation as well as payroll. A PEO takes on more of your HR, benefits and compliance work, which can give a small team access to benefits it couldn't arrange alone. If you only need people paid and taxes filed, a payroll plan is simpler; if benefits and HR advice matter, ask both for a PEO proposal.
Questions to ask in the demo
- Which product or plan fits our headcount now, and in two years?
- Which states do we need payroll tax filing in?
- Can employees see payslips and update details themselves?
- Which accounting and time tracking tools does it connect to?
If you're also choosing HR software, see my guide to HR software for small businesses, and if you're self-employed, this guide on creating a paystub covers the basics.
Compliance help beyond the payslip
Payroll mistakes are rarely about the payslip itself; they're about rules. ADP's compliance services cover business tax credits, payroll taxes, wage garnishment, unemployment claims, employment verification and contractor management. Paychex publishes state compliance resources that show obligations such as tax rates and minimum wage, and offers HR consulting for questions your team can't answer alone. Paychex also lists time and attendance tools, including time clocks, to save time and prevent errors.
My advice on ADP or Paychex
Get a demo from both with your real headcount, states and benefits needs on the table. If you expect to grow well past 50 staff, ask ADP how its products connect as you move up a size band. If you want clear tiers and plenty of HR help in one plan, look closely at Paychex Advanced or Complete. Choose the one whose demo answers your four questions without follow-up emails.
Do you make payroll or HR software? Tool makers can ask to be considered for a featured place in comparisons like this one.
Frequently asked questions
Which ADP product is for small businesses?
ADP offers RUN Powered by ADP for businesses with 1-49 employees.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
What plans does Paychex offer?
Paychex lists Basic, Foundations, Advanced and Complete plans for small business payroll.
Do ADP and Paychex file payroll taxes?
Yes. Paychex says it calculates, pays and files payroll taxes automatically, and ADP lists payroll tax compliance services.
Do both offer a PEO?
Yes. ADP offers ADP TotalSource and Paychex offers a PEO alongside its payroll plans.
How many clients does Paychex have?
Paychex says it's trusted by about 840,000 clients.
Which is better for a growing company?
ADP sells different products for 1-49, 50-999 and 1,000+ employees; Paychex scales through its plan tiers. Ask both how moving up works.
Does ADP have an app store?
Yes. ADP runs an online store of HR apps and integrations.
Can Paychex process card payments?
Paychex lists payment processing for credit cards, debit cards, ACH payments and eChecks.
