Spending for the Department of Health and Human Services would increase to $1.1 trillion under a proposal that would add large mandatory expenditures for cancer research and fighting drug addictions while slightly decreasing the department’s discretionary programs.

The budget would modify the controversial “Cadillac tax” on expensive private health plans, so that it wouldn’t apply to some employers in states with especially high insurance prices. The tax, part of the Affordable Care Act, already has been postponed from 2018 to 2020.

The budget proposes several steps to address the escalating price of prescription drugs. It would enable the government to compel pharmaceutical manufacturers to disclose the cost of researching and developing drugs. It calls for speeding up the closing of a “donut hole” in Medicare drug benefits and for bigger drug rebates for low-income Medicare patients.

The budget furthers the administration’s efforts to move toward new payment methods in Medicare, including a new competitive bidding system for private Medicare Advantage health plans.

The proposal also reinforces the administration’s push for more states to expand Medicaid under the ACA. It would allow the federal government to pay the entire cost of such expansions for three years, no matter when a state made its decision. Currently, the federal portion is scheduled to dip to 90 percent next year.

The White House is highlighting $500 million that would be devoted to treating serious mental illnesses — part of a package of executive actions to try to curb gun violence announced last month.