The 90-day checklist for leaving a Professional Employer Organization.

Why the sequence matters more than the date.

Employers leaving a Professional Employer Organization typically anchor to a January 1 or a July 1 transition date. The date is the easy part. The sequence — which registrations open first, which accounts must exist before the first payroll runs, which year-end reconciliations are the employer's obligation — is where transitions succeed or quietly fail.

The checklist below is the sequence we run for every transition. It is 90 days for a reason: state agencies take four to eight weeks to issue account numbers, benefits carriers require 30 to 60 days notice, and the year-end wage reconciliation cannot start until both entities agree on the transition-date wage base.

Days 1 to 30 — architecture.

• Enumerate every state with active wages (including remote employees). This is the exposure map — nothing else can be sequenced until it exists.
• Open state income tax withholding accounts in every state on the map.
• Open state unemployment insurance accounts. Confirm whether the state permits Common Paymaster or successor-employer transfer of the experience rating; the answer is state-specific and dispositive on the first-year rate.
• Register for local jurisdiction obligations — Pennsylvania Act 32 (Berkheimer or the local designee), Ohio RITA and municipal locals, Oregon transit districts, New York MCTMT, and any other special-purpose district on the map.
• Confirm Federal Employer Identification Number, apply for a new one only if the entity is restructuring alongside the transition.
• Notify the Professional Employer Organization in writing of the exit date and request the wage-base reconciliation packet.

Days 30 to 60 — systems.

• Select and contract the payroll processing platform. Confirm multi-state deposit and filing capability for every jurisdiction on the map.
• Set up benefits carriers under the employer's own group — health, dental, vision, life, disability, retirement plan. New group numbers, new plan documents, new open enrollment.
• File Section 125 Cafeteria Plan documents and the new plan document for the retirement plan (typically a 401(k) with the same match structure to avoid employee disruption).
• Confirm workers' compensation coverage in every state. Coverage under the Professional Employer Organization's master policy ends on the exit date; new coverage must be effective the following day without a gap.
• Document the transition communication for employees: pay date changes, benefits enrollment windows, new deduction line items, direct deposit re-verification.

Days 60 to 90 — cutover.

• Run parallel payroll for the last cycle before cutover. Reconcile gross wages, tax withholding, and net pay against the Professional Employer Organization's final calculation.
• Confirm every state and local tax deposit for the transition-date pay period is filed by the correct entity — the Professional Employer Organization for wages earned before, the employer for wages earned after.
• Distribute the transition communication package to employees at least 14 days before the first employer-run payroll.
• Execute the first employer-run payroll. Verify every jurisdiction's deposit clears and every deduction line reconciles.

The year-end reconciliation that catches everyone.

In the calendar year of the transition, employees will receive wages reported under two Federal Employer Identification Numbers — the Professional Employer Organization's for wages earned before the exit, and the employer's for wages earned after. Whether the wage bases for Social Security, Medicare Additional, FUTA, and state unemployment reset depends on the state and on whether Common Paymaster or successor-employer status was successfully established during registration.

The reconciliation is the employer's obligation. Skipping it results in over-withheld Social Security (refundable to the employee via Form W-2c and the employee's tax return), over-deposited FUTA (refundable via Form 940 credit reduction), and mismatched state unemployment reporting (potentially triggering state-level notices).