If I change jobs mid-year, can I contribute to two different 401(k)s?

Yes, you can contribute to both employers' plans, but your personal deferral limit is a single annual cap across all of them combined — $23,500 in 2025, plus $7,500 if you're 50 or older. The plans don't talk to each other, so it's on you to track the total. If you maxed out at your old job, contribute $0 of your own salary at the new one to avoid an excess deferral; if you put in $15,000 before leaving, you have only $8,500 left for the new plan. Note that each employer's match is separate and doesn't count toward your $23,500 — only your own contributions do. Excess deferrals must be corrected by April 15 of the following year or you'll be taxed twice. Tally your year-to-date contributions from both W-2s before December to stay under the limit.