payroll_tax_gross_wages adds irs_employment_income, which subtracts pre_tax_contributions (including traditional_401k_contributions and traditional_403b_contributions). Per IRS rules, traditional 401(k) and 403(b) (as well as 457(b), and SIMPLE IRA) elective deferrals reduce Box 1 (federal income wages) but do not reduce Boxes 3 and 5 (SS/Medicare wages). The FICA base (payroll_tax_gross_wages) should be the sum of these together with irs_employment_income.
payroll_tax_gross_wages adds irs_employment_income, which subtracts pre_tax_contributions (including traditional_401k_contributions and traditional_403b_contributions). Per IRS rules, traditional 401(k) and 403(b) (as well as 457(b), and SIMPLE IRA) elective deferrals reduce Box 1 (federal income wages) but do not reduce Boxes 3 and 5 (SS/Medicare wages). The FICA base (payroll_tax_gross_wages) should be the sum of these together with irs_employment_income.