Added copy & paste info:
Keep in mind, the 4% payroll tax isn't going to cover all of the expenses. It would be helpful to also list the other proposed mechanisms of paying for M4A:
Creating a 4 percent income-based premium paid by employees, exempting the first $29,000 in income for a family of four
Imposing a 7.5 percent income-based premium paid by employers, exempting the first $2 million in payroll
Eliminating health tax expenditures
Making the federal income tax more progressive, including a marginal tax rate of up to 70 percent on those making above $10 million
Making the estate tax more progressive, including a 77 percent top rate on an inheritance above $1 billion
Establishing a tax on extreme wealth
Closing a tax-loophole that allows self-employed people to avoid paying certain taxes by creating an S corporation
Imposing a fee on large financial institution
Repealing corporate accounting gimmicks
https://m.dailykos.com/stories/2019/4/11/1849524/-Bernie-s-revised-M4A-bill-is-here-what-s-changed
I've been questioned about this before so it'll be handy to know these when discussing this with potential voters.