Republicans in Congress have spent a lot of time this year arguing about the need to pay for new spending with offsetting budget cuts.  But what about paying for tax cuts?

Before you shower me with emails about how tax cuts spur new jobs and end up bringing in more revenue to Uncle Sam, that's not really how things are "scored" by the budget scorekeepers over at the Congressional Budget Office.

What matters to them is that less money will be coming into the U.S. Treasury, which has to be "paid for" in some manner.

Why do I bring this up now?  Well, at some point this year, the Congress will have to confront the reality that the Bush Tax Cuts are expiring.

And that will cost the feds more than $2 trillion over ten years, because if you extend those tax cuts, then the expected revenue won't be flowing into federal coffers.

Democrats have been making some noise about this issue, because Republicans in the Senate have been holding up a bill that extends long term jobless benefits, demanding that Democrats pay the cost of the bill, estimated at $33 billion over six months.

Lawmakers can't agree on how to pay $33 billion, so there is almost no way they are going to agree on more than $2 trillion, obviously.

This is the reason that Congress has to "patch" the Alternative Minimum Tax, so it doesn't hit as many people each year, instead of just repealing it.

Because it you get rid of the AMT, you somehow have to make up for the "lost" revenue that would have come into the feds.

It's just one of many reasons that Congress has reached budget and tax gridlock.  No one can agree on what should or should not be "paid for" and certainly, no one can agree on how to make any cuts in the first place.

One final note - why do the Bush Tax Cuts "expire" after ten years?  Why wouldn't they just live on in perpetuity like other changes to federal law?

Well, that's because of the "Byrd Rule", so named for the late Sen. Robert Byrd (D-WV).  It does not allow the Congress to approve budget or tax provisions that would increase the deficit after ten years.

And since "tax cuts" would take money from the Treasury, they would increase the deficit - and so - they lapse after ten years.

For now, that's one of the many legacies of Sen. Byrd.