The latest IRS rules on 401(k) contribution maximums are here. It’s time to start planning. - iStock/MarketWatch illustration Millions of workers saving for retirement now know how much money they can stash next year in 401(k)s and other tax-advantaged retirement accounts. The annual announcement from the Internal Revenue Service may have extra significance in 2026, as 401(k) contributions become a valuable tool many can use to ensure they’re making the most of new tax breaks in President Donald Trump’s ...