I've read that the IRS has no recourse for collecting from those who refuse to pay the Obamacare penalty. Has anyone tested this out?

Under the Obama administration, if you owed a tax “penalty” it was simply deducted from your refund, assuming you were owed a refund. If your refund was not enough to cover the penalty, you would be expected to pay up - but other than being told you have to pay there was no further enforcement.

This set it up so each year, if you made sure you were never owed a refund, it would just keep carrying the penalty forward to the next year, but the moment you were otherwise supposed to get a refund it would get deducted from that.

Kind of a passive aggressive-solution, but it was a functional way handle enforcement without going out of their way to hunt people down.

Under the new Trump administration, no one knows what will happen. Trump’s statement on the issue essentially admitted he had no idea what legal power he had to waive the penalty like he wants to, but an act of Congress could certainly get the job done and this Congress just might do it.