How do I split my 401(k) contribution between traditional and Roth in the same plan?

Many plans let you direct part of each paycheck's deferral to the pre-tax (traditional) bucket and part to the Roth bucket simultaneously, using percentages you set in your provider's portal. Your combined traditional plus Roth deferrals still count against the single IRS employee limit, so splitting does not let you contribute more overall.

A common approach is to hedge: put some in Roth for tax-free growth and some in traditional for an upfront deduction, especially if you are unsure whether your tax rate will be higher now or in retirement. Note that any employer match has historically gone into the pre-tax side by default, though SECURE 2.0 now permits Roth matching if your plan offers it. The Roth vs Traditional calculator at wealthserene.com/tools/roth-vs-traditional can help you weigh the split.