Congress wants to overhaul retirement plans. Here’s what might be coming.

Tucked halfway down into a 4,155-page spending bill that proposes $1.7 trillion to fund the federal government through much of 2023 are proposed changes to how retirement plans work. Intended to boost retirement savings and access to 401(k) and individual retirement accounts, the Secure Act 2.0 is aimed at low- and middle-income workers, those strapped with student debt and people who may not yet have a long-term retirement account.

Will Hansen, the chief government affairs officer with the American Retirement Association, which advocated for Secure 2.0, told The Washington Post it’s the largest bill...