Guaranteeing health care coverage for all, including undocumented immigrants, begs one question -- who would pay for it?

The Healthy California Act, which would create a single-payer health care system and guarantee coverage, is scheduled to be heard in a state Senate committee at the end of the month. So we tried to answer the cost question. 

Here's what we found out:

Details remain scarce in the bill, but according to state Senate Committee on Health analysis, it would involve the transfer of existing spending, such as Medicare, into the single-payer system.

Most Californians -- almost 60 percent -- get health insurance through their employer. That spending would need to be shifted to the state as well. 

"This is substituting one cost that comes out of our payroll for another," University of California, Los Angeles health policy professor Gerald Kominski said. 

Kominski calculated that private health care, which includes not only employer insurance, but out-of-pocket expenses and individually purchased insurance, costs $106.6 billion

Critics argue that single-payer health care would raise taxes and wait times, while supporters say the state managing health care would eliminate administrative costs. 

However, it's worth noting that multiple versions of this bill have failed since 2004.