“Is my 401(k) contribution pre-tax or post-tax?”

It can be either — and many plans now offer both, which is where the confusion usually starts.

A *traditional* 401(k) contribution comes out of your paycheck before income tax is calculated. You pay less tax today, and instead pay tax later, when you withdraw in retirement.

A *Roth* 401(k) contribution is the reverse: taxed now, then generally tax-free when you withdraw it in retirement (subject to the plan's rules).

Neither is universally better — it mostly turns on whether you'd rather pay tax at today's rate or your future rate, and no one knows future rates for certain. Your paystub will show which type you're currently making; if the line says "Roth," it's post-tax. If you're not sure which you picked when you enrolled, that's a normal thing not to remember — your plan portal shows it.