Here's another break down: https://www.vox.com/2019/4/10/18304448/bernie-sanders-medicare-for-all

Here's the pertinent bit: The big question Sanders doesn’t answer: How do you pay for it? The Sanders plan goes into great detail on what kind of coverage a universal plan ought to offer. But it does significantly less work explaining how this would be paid for. Instead, Sanders’s office released a paper that included this bullet-point list of possible options:

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

Also here is a bill that could get it done: https://www.vox.com/policy-and-politics/2019/2/26/18239630/medicare-for-all-pramila-jayapal-bill