You have to complete signup by December 23 to be covered from January 1, but the insurance companies were asked and agreed to cover retroactively if payment is made by a later date (maybe January 10, I'm not sure). I called my new insurance company and they said to send the first month's amount, after which they will send the welcome kit and cards. Future payments will be made however they usually handle it.

What if you are below the poverty level and your state has refused the medicaide expansion?

will waive the penalty.

Some states are horribly mean in who they'll cover with Medicaid.

I am one who sincerely hopes that this will lead, in a very few years, to something along the lines of a single payer system.