Embed the Finch Connect button or SDK in your benefits platform UI; configure the Connect session with the deductions product scope to request write access
After the employer completes the Connect flow, store the access_token securely — it represents that employer's consent to write payroll data
Create the 401k benefit at the company level: POST /employer/benefits with benefit_type set to the appropriate 401k code and contribution details
Enroll each participating employee: POST /employer/benefits/{benefit_id}/individuals with each employee's individual_id and their elected pre-tax and/or Roth contribution amounts
Verify enrollments before the payroll close date with GET /employer/benefits/{benefit_id}/individuals; check each record's enrollment status field
After each payroll run, retrieve contribution actuals and reconcile against elected amounts; report discrepancies to both the employer and the retirement recordkeeper
Known gotchas
Write support for 401k deductions is provider-dependent; some payroll systems connected via Finch only support read — check the Finch provider capability matrix for deductions write support before promising write functionality to your customers
For assisted-connection providers, submit elections at least 7 days before the payroll close date; for automated connections, meet the provider's own close date cutoff
Roth (after-tax) 401k elections are a separate deduction type from pre-tax; ensure your benefit creation payload correctly distinguishes the two to avoid incorrect tax treatment
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