President Obama has persistently tried to have it both ways when it comes to the Medicare cuts in his signature health care law. He and others in his administration have repeatedly claimed that the law extends the solvency of Medicare and is fully paid for. Both claims can’t be true.

Earlier today, I was able to catch up with Richard Foster, the chief actuary of the Center for Medicare and Medicaid Services, before he testified to the House Budget Committee, and I asked him to explain the complicated “double counting” issue. I’ve transcribed the full explanation below, but the key point is that the same money cannot be used twice, even though though the quirky trust fund accounting conventions of our entitlement system would seem to suggest that this is possible.