Payroll Tax Specialist - Multi-State; Part-time or Contractor

Our client is a clinical stage biotechnology company developing therapeutics founded by Mass General Brigham Ventures, Massachusetts General Hospital and Brigham & Women’s Hospital and has laboratory and office space in Boston.

We are looking for a payroll tax professional with deep, hands‑on expertise in ADP Workforce Now (WFN) and multi‑state payroll tax compliance. This role starts with a comprehensive audit of our current state‑by‑state setup, then transitions into ongoing, as‑needed support — registering us in new states, maintaining Third Party Administrator (TPA) access, managing state unemployment insurance (UI) and state tax , coordinating with ADP, and reviewing payroll for accuracy whenever our employee or work‑location footprint changes.

This is not a full‑time role. We expect a few hours per week, on an as‑needed basis, with workload

fluctuating around new hires, new state registrations, and periodic compliance reviews.

Before any new setup work begins, we need this person to:

• Review our current ADP WFN configuration across all states where we have employees
• Determine, state by state, what ADP is filing/remitting on our behalf versus what remains our responsibility (e.g., certain local or state filings ADP does not cover)
• Identify any gaps, missing registrations, delinquent filings, or compliance risks
• Confirm TPA authorizations are properly in place wherever ADP needs them to file for us
• Deliver a clear summary: current state‑by‑state status, what's working, what's missing, and recommended next steps/priority order to get fully compliant

• New State Set‑Up (End-to‑End)
• Determine registration requirements when we hire in a new state
• Apply for and obtain all required state IDs:
  State Unemployment Insurance (SUI/UI), State Income Tax Withholding, and any other state‑specific tax accounts
• Set up and confirm TPA access so ADP can file/remit on our behalf wherever applicable
• Supply new state IDs and account information to ADP and ensure they're correctly loaded into WFN
• Track registration status end‑to‑end until the state is fully active and filing correctly

• Handle the distinct registration and compliance process required in monopolistic states (e.g., ND, OH, WA, WY), where workers' compensation coverage must be obtained through the state fund rather than a private carrier
• Ensure these states are properly set up and coordinated with ADP alongside standard tax/UI registrations

• Serve as the point person for any state correspondence related to UI rates, tax , notices, or compliance issues
• Communicate with state agencies directly when needed (registration, rate inquiries, notice resolution)
• Keep ADP WFN records in sync with what's actually registered/active at the state level

• When we have changes like a new employee, relocation, remote work changes, or multi‑state work situations, review the payroll setup to confirm:
• Correct state/locality tax withholding is applied
• SUI/SIT assignments are accurate
• Reciprocity agreements (where relevant) are correctly applied
• No missing or misconfigured state tax elements before payroll runs

• Proven, hands‑on experience administering ADP Workforce Now, specifically around state tax setup, not just day‑to‑day payroll processing
• Strong working knowledge of multi‑state payroll tax compliance: SUI/UI, state income tax withholding, reciprocity agreements, and state‑specific quirks
• Direct experience registering employers for new state tax IDs and setting up TPA authorizations
• Familiarity with monopolistic workers' compensation states and their distinct setup requirements
• Comfortable interfacing directly with state agencies (UI departments, state tax/revenue departments)
• Detail‑oriented, able to independently audit a company's current compliance posture and flag gaps clearly
• Can work independently with minimal oversight; this is a part‑time/as‑needed engagement, so self‑direction matters

• Experience supporting a multi‑state employer going through rapid headcount or geographic growth
• Background in payroll and state HR compliance