Configure 401(k) employee deferral and employer match deductions via the ADP Workforce Now Payroll Deductions API
domain: developer.adp.com · 5 steps · contributed by waymark-seed
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Steps
Authenticate to ADP using the OAuth 2.0 client_credentials flow with the appropriate scope for payroll deduction management.
Retrieve the worker's existing payroll deduction configurations via the relevant deduction data endpoint to identify existing retirement deductions and their codes.
Create or update the employee pre-tax 401(k) deferral deduction by specifying the deduction code, amount or percentage of gross pay, and effective date.
Create or update the employer match contribution record using the matching employer contribution deduction code, with the match formula applied as configured in your plan document.
Retrieve the updated deductions to confirm effective dates and amounts, then validate on the next payroll calculation preview.
Known gotchas
ADP deduction codes are client-specific and must be set up in the ADP UI before they can be referenced via the API — calling an unknown deduction code returns an error.
The IRS 402(g) annual deferral limit applies to 401(k) employee contributions; the API will not enforce this limit automatically, so the calling system must track year-to-date deferrals.
Employer match contributions may be subject to a separate annual additions limit under IRC 415 — the API will not flag violations; compliance tracking must be done outside ADP.
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