Payroll onboarding

How to onboard a new payroll client

Payroll onboarding has a hard start date: the first pay date. The firm needs the registrations, the employee forms and the prior payroll history before that date, or the first paycheck is late and the year-to-date totals are wrong. This guide covers the sequence for a new payroll client, including a mid-year switch.

Reviewed November 3, 2026 · 3 min read

Sketch: the payroll onboarding checklist as a client sees it on a phone in UsualHarbor Tax & AccountingPayrollonboarding27 items · due FridayLegal business name…Payroll bank accountPay schedule and firs…State withholding…State unemployment…Continue

Key takeaways

  • Work backward from the first pay date.
  • Confirm the state withholding and unemployment accounts before the first run.
  • Get the year-to-date register and the filed payroll returns if the client switches mid-year.
  • Run a preview and get the client's approval before the first payroll is submitted.

Before the first payroll

Set the first pay date and the payroll frequency. Work backward to the date the firm needs the employee records, the bank account and the approvals.

Confirm the legal name, EIN, payroll bank account and the pay schedule. A missing bank account or a wrong EIN delays the first tax deposit.

Confirm the registrations

Get the state withholding and unemployment account numbers for each state where employees work. A payroll provider can usually file only after the accounts are active.

Check local tax registrations and any state new hire reporting requirement. A registration that is missing on the first pay date becomes a penalty later.

Collect the employee records

Get each employee's legal name, address, hire date, pay rate, W-4 and state withholding form. The employer keeps the I-9; the payroll provider usually needs confirmation that it is complete.

Set up direct deposit through the provider's self-service portal where possible. Do not collect bank account numbers in an email.

Collect the benefits deductions, garnishments and PTO balances before the first payroll, not after.

Get the prior payroll history

If the client is switching mid-year, get the year-to-date payroll register, the Forms 941 filed so far, the state payroll returns and the last pay stubs.

Check that the prior provider's year-to-date totals agree with the filed returns. A difference will show up in the annual W-2s if it is not fixed now.

Run the first payroll

Run a preview and send it to the client for approval before the provider's cutoff. The client should check the hours, the new hires and the deductions.

After the payroll is submitted, check the tax deposits and the pay date. The first payroll is the test of the whole setup.

Close the first quarter

File the first Forms 941 and state payroll returns on time, and reconcile the deposits to the returns.

Review the first quarter with the client: the payroll cost, the tax deposits and any employee question. Fix the setup before the second quarter.

Questions about this guide

What is needed to start payroll for a new client?

Start with the EIN, the payroll bank account, the pay schedule, the state registrations and the employee roster with Forms W-4 and state withholding forms. If the client switches mid-year, add the year-to-date register, the filed payroll returns and the last pay stubs.

What is Form 8655 used for?

Form 8655 authorizes a reporting agent to file payroll tax returns and make deposits for the client. The client signs it, and the firm keeps it with the payroll engagement records.

Can a client switch payroll providers mid-year?

Yes. The new provider needs the year-to-date register, the payroll tax returns filed so far and the last pay stubs, so the annual W-2s and the quarterly returns agree at year end.

Who enters direct deposit details?

Have employees enter their own bank details in the payroll provider's self-service portal where possible. If the firm collects the details, use a secure field and never put account numbers in an email.

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Sources

Checked November 3, 2026. Public pages and tax rules change; confirm them before relying on them.

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