If you recently enrolled in a 401(k) plan and noticed your take-home pay decrease, this is completely normal.
A 401(k) deduction is taken directly from your gross wages before your paycheck is issued. When it appears as a pre-tax deduction (often labelled px401 EEPRE or similar), it reduces your taxable income — but it still lowers your net pay.
That means:
Gross pay goes down by your contribution amount
Taxable wages are reduced
Federal income tax is calculated on a lower figure
Net pay decreases — but not dollar-for-dollar
Why the Impact Isn’t Equal to the Contribution
Example:
Monthly salary: $4,000
401(k) contribution: $400
Taxable income becomes $3,600 instead of $4,000.
Because income tax is calculated on $3,600, your real take-home reduction may feel closer to $300–$340 depending on your tax bracket.
If your paycheck shows codes like PX401 EEPRE, that label typically represents this type of pre-tax retirement contribution.
Does a 401(k) Reduce All Payroll Taxes?
In most cases:
It reduces federal income tax
It may reduce state income tax
It does not reduce Social Security or Medicare taxes
Always verify with your payroll department for plan-specific treatment.
Why This Matters Long Term
Pre-tax contributions defer taxes until retirement. You benefit from:
Lower taxable income today
Tax-deferred investment growth
Compounding over time
For a detailed explanation of payroll code formatting, see our guide on the PX401 EEPRE deduction.
FAQs
Why is my paycheck smaller after enrolling in a 401(k)?
Because contributions are deducted from your wages before your net pay is calculated.
Does stopping my 401(k) increase my paycheck?
Yes. Your taxable wages increase, which raises take-home pay but reduces retirement sav