Several Republican senators want the IRS to clarify how Obamacare’s individual mandate will be enforced amid questions about penalties for people who don’t get insurance coverage. The lawmakers are asking the IRS to describe how it will pursue payment of the penalty, which goes into effect this year. In a letter sent to the agency, the group questions whether the IRS will collect payment on the penalty and accrued interest when a person sells property — a scenario that a Congressional Research Service report said was a possibility.

The lawmakers also ask how broadly the “hardship exemption” from the mandate’s penalties will be applied and if Americans who unknowingly qualify for an exemption from the mandate yet pay the penalty will be reimbursed. The Obama administration is expected to be under significant pressure to not have fines issued in such a circumstance. The letter was signed by Sens. Lamar Alexander, Tom Coburn, Jeff Sessions, John Barrasso, Jerry Moran and John Cornyn.