Sources familiar with the Republican tax negotiations say there’s an acknowledgment within the working group that setting the corporate rate at less than 25 percent may be unworkable if the tax reform is going to be revenue neutral.

Why it matters: This is far from the number the administration wants, but a source familiar with the discussions said it’s a simple numerical cash problem. They’ve done away with the border adjustment tax, health care repeal is failing, and there are no politically-palatable alternatives to fill more than $1 trillion in missing revenue.