"Please describe the methods the IRS intends to use to enforce payment of the tax.... [D]oes the IRS anticipate taking the tax from a person's refund would be an effective method for ensuring compliance with the individual mandate tax? ... Will individuals who completed all the steps to purchase health insurance, but were not enrolled due to a website error be required to pay the tax? ... How does the IRS intend to verify the coverage gap did not exceed the three-month threshold?"