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Payroll · head to head

OnPay vs Paychex Flex

OnPay logo

OnPay

Payroll

Single-plan United States payroll with unlimited pay runs and support for awkward tax situations other providers avoid

From
On request
Rated
-
Full reviewWebsite
Paychex Flex logo

Paychex Flex

Payroll

Payroll and HR solutions that grow with you

From
$39/month
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: OnPay onPay operates only in the United States, so the first international hire means a second payroll vendor and a separate compliance model.; Paychex Flex no published pricing rates available
  • They diverge on capability: OnPay covers Single plan, Paychex Flex covers Payroll Processing.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which OnPay and Paychex Flex actually diverge.

Attributes where OnPay and Paychex Flex differ
AttributeOnPayPaychex Flex
Starting priceOn request$39/month
PlatformsWebWeb, Ios, Android
FoundedUnknown1971

Identical on both: pricing model (quote), free tier (No), user rating (Not yet rated), category (Payroll).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in OnPay

  • Single plan
  • Tax filing and payment
  • Vertical payroll support
  • Benefits brokerage
  • Workers compensation
  • Contractor payments
  • Basic HR tools
  • Accounting integrations

Only in Paychex Flex

  • Payroll Processing
  • Tax Administration
  • HR Services
  • Benefits Administration
  • Time and Attendance
  • Retirement Services
  • QuickBooks
  • Xero

What people use each for

The jobs each tool is most often brought in to do.

OnPay

  • A farm running agricultural payroll that needs Form 943 rather than the standard quarterly filingnot Paychex Flex
  • A church or nonprofit with clergy compensation rules that mainstream providers decline to handlenot Paychex Flex
  • A restaurant group needing tip credit and minimum wage make-up calculated correctly each pay periodnot Paychex Flex
  • A small business that wants one price for payroll rather than a tiered plan it has to keep upgradingnot Paychex Flex

Paychex Flex

  • Running payroll and filing payroll taxes for small and mid sized US businessesnot OnPay
  • Combining payroll with benefits administration and HR services from one vendornot OnPay
  • Handling multi state payroll compliance and year end tax formsnot OnPay

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

OnPay

  • OnPay operates only in the United States, so the first international hire means a second payroll vendor and a separate compliance model.
  • There is no native mobile application, only a responsive web interface, which employers with field or shift-based staff notice immediately.
  • The HR functionality is administrative and does not replace an HRIS, so performance, learning and any real workflow automation need another product.
  • Time and attendance is handled through integrations rather than natively, meaning hours arrive from a third-party system that has to be reconciled when it disagrees with payroll.
  • Reporting is functional but limited, and companies that want cost analysis by department, project or location generally export to a spreadsheet rather than build it in the product.

Paychex Flex

  • No published pricing rates available
  • Pricing varies significantly based on employee count and business needs
  • All pricing requires direct contact with sales team

Pricing, plan by plan

OnPay

On request
  • OnPay$undefined/month
    • One published plan combining a flat monthly base fee with a per person charge
    • No feature tiers, upgrades or add-on modules
    • Unlimited pay runs and multi-state filing included

Paychex Flex

$39/month
  • Essentials$39/month
    • Payroll Processing
    • Tax Services
    • Direct Deposit
  • Select$undefined/month
    • All Essentials features
    • HR Administration
    • Onboarding

Which should you pick?

Choose OnPay if

  • You need single plan.
  • You also want tax filing and payment.
OnPay review

Choose Paychex Flex if

  • You need payroll processing.
  • You work on Web, Ios, Android.
  • You also want tax administration.
Paychex Flex review

Questions people ask

Is OnPay or Paychex Flex better?
Neither clearly leads. OnPay starts at On request and Paychex Flex at $39/month, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, OnPay or Paychex Flex?
OnPay starts at On request and Paychex Flex at $39/month.
Does OnPay or Paychex Flex run on more platforms?
OnPay runs on Web. Paychex Flex runs on Web, Ios, Android.
What is OnPay best used for?
OnPay is most often used for a farm running agricultural payroll that needs form 943 rather than the standard quarterly filing, a church or nonprofit with clergy compensation rules that mainstream providers decline to handle, a restaurant group needing tip credit and minimum wage make-up calculated correctly each pay period, a small business that wants one price for payroll rather than a tiered plan it has to keep upgrading. Of those, a farm running agricultural payroll that needs form 943 rather than the standard quarterly filing and a church or nonprofit with clergy compensation rules that mainstream providers decline to handle are not what Paychex Flex is typically brought in for.
What can OnPay do that Paychex Flex cannot?
OnPay covers Single plan, Tax filing and payment, Vertical payroll support, Benefits brokerage. Paychex Flex covers Payroll Processing, Tax Administration, HR Services, Benefits Administration.

Answered from the vendors’ own pages

OnPay: How is OnPay priced?

As a single published plan with a flat monthly base fee plus a charge per person paid, with no feature tiers. Contractors are charged at the same per person rate as employees.

Paychex Flex: How much does Paychex Flex cost?

Paychex does not publish specific pricing rates. Pricing depends on your employee count and specific business needs. Customers must contact the sales team at 833-729-8200 or use the Request Pricing option for a custom quote.

Source
OnPay: Does it handle payroll outside the United States?

No. It is US-only, in all fifty states, including multi-state filing at no extra cost.

Paychex Flex: What Paychex Flex packages are available?

Three main payroll packages are offered: Paychex Flex Select, Paychex Flex Pro, and Paychex Flex Enterprise. There is also an Express package for specific scenarios like one-employee payroll.

Source
OnPay: Why do farms and churches use it?

It supports Form 943 agricultural filing, clergy housing allowance and Social Security exemption rules, and 501(c)(3) nonprofit payroll, which several larger providers do not.

Paychex Flex: Does Paychex offer promotional pricing?

Paychex offers a promotion providing three months of free payroll services for new clients who process their first payroll by June 18, 2027, and maintain continuous payroll processing for 12 consecutive months. Eligible companies have 1-250 employees.

Source
OnPay: Is there a mobile app?

No. Employers and employees use a responsive web interface, which is a genuine gap for shift-based workforces.

Paychex Flex: What factors affect Paychex Flex pricing?

Pricing is based on employee count, specific features needed including HR, benefits, time tracking, insurance, and your chosen service tier.

Source
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