In a revamped health care system envisioned by senators, people would be required to carry health insurance just like motorists must get auto coverage now. The government would provide subsidies for the poor and many middle-class families, but those who still refuse to sign up would face fines of more than $1,000.

The Congressional Budget Office estimated the fines would raise around $36 billion over 10 years. Senate aides said the penalties would be modeled on the approach taken by Massachusetts, which now imposes a fine of about $1,000 a year on individuals who refuse to get coverage. Under the federal legislation, families would pay higher penalties than individuals.