Map payroll earning codes to the 401(k) plan's compensation definitions

Retrieve the signed plan document, adoption agreement and relevant amendments before checking payroll settings. A benefits summary can omit distinctions the actual plan makes. The IRS explains that a plan may use different compensation definitions for employee deferrals, employer allocations and compliance testing.

Ask the plan administrator to identify each applicable definition and effective period. Record the specific provisions supporting the interpretation. If the plan changed during the year, identify when the payroll configuration should have changed and whether prior-period data needs separate treatment.

Export the active and recently used payroll earning codes, including manual and off-cycle codes. Include bonuses, commissions, overtime, taxable benefits, severance and reimbursements where relevant. The administrator should decide how each code fits the plan's definitions; finance should supply an accurate description of what the code actually pays.

Do not rely on the code's name alone. A code labeled 'miscellaneous' may contain both compensation and genuine reimbursements. Review its transactions and split mixed uses before asking the administrator to assign a retirement-plan treatment. Otherwise one checkbox applies to materially different payments.

Choose employees whose compensation includes the exceptions the plan addresses. Recalculate the eligible compensation base from their actual earning detail, then compare the result with payroll's deferral and match calculations. A salary-only example cannot demonstrate whether a bonus exclusion was configured correctly.

For a hypothetical employee with $3,000 of regular wages and a $500 bonus, the relevant base could differ depending on the plan's definitions. Do not choose between $3,000 and $3,500 without the administrator's instruction. Record the selected base separately for each plan purpose.

Check any compensation limits using the correct plan year and applicable rules. The test should also account for the employee's election and eligibility period. A difference in contribution amounts may come from those inputs rather than the earning-code mapping itself.

If a code was wrong, preserve the prior configuration and identify the affected employee population and pay periods. Correcting the checkbox today prevents future errors but does not resolve missed or excess contributions already made. The IRS fix-it guide describes potential corrective contributions, reallocations or distributions depending on the facts.

Give the administrator an employee-level impact file and ask for an approved correction method. Do not withdraw money from participant accounts or increase deductions from future pay merely to make annual totals match. Different kinds of errors require different remedies and may involve earnings adjustments.

Keep the correction instructions separate from the new payroll configuration approval. Confirm both were implemented. The person changing payroll settings and the recordkeeper allocating a corrective contribution may work in different systems and need distinct completion evidence.

Require retirement-plan mapping when payroll introduces a new compensation code. Record the business purpose and obtain the administrator's treatment before the code is used. A new sales incentive or taxable allowance should not inherit an unrelated code's settings merely because it is convenient.

Save the final mapping with the plan version and reviewed examples. Revisit it when amendments or compensation practices change. That gives the next payroll administrator an explanation of each setting, rather than a list of checkboxes whose original reasoning has been lost.