At the top of the Congressional agenda for the remainder of this week will be extending the payroll tax cut. Whatever its merits, the extension is a done-deal. Both parties agree on it and it’s just a matter of assembling a way of paying for it. Both parties also understand that, despite their rhetoric, neither millionaires or federal employees will be bearing the full cost of the extension.

One of the “off-sets” being discussed is an increase in the guarantee fees (g-fees) that Fannie Mae and Freddie Mac charge to cover the credit risk in mortgages that they purchase. Not surprisingly, my friends in the real estate industry have come out against the proposal. NAHB goes as far to say, “This will jeopardize the tenuous rebound and is the last thing this economy needs.”

Accepting that the language is currently in flux and it is not even a given that the g-fee increase will be included, I believe my real estate friends are over-reacting. As presently proposed, the increase would only be 10 basis points (which are 1/100 of a percentage point) a year. This is so modest as to have about zero impact on the housing market. Mortgage rates fluctuate by more over the course of a day.

What I am worried about is that the change is instituted over a 10 year period. Putting aside the bizarre policy of using 10 year “revenue-raisers” to pay for one year of spending, the policy might actually make it harder to eliminate Fannie and Freddie. Why? Let’s say the next Congress and White House administration put the taxpayer above the special interests and decide to end Fannie and Freddie. Now you might have to “pay” for ending them, as their existence has been built into the 10 year budget baseline.

The simple solution to me would be to limit the increase to 5 years. I don’t think anyone really expects the GSEs to disappear before then. We could raise the same amount by increasing the g-fee bump to say 20 basis points, which would also have the advantage of making the GSEs less competitive with other sources of mortgage capital, allowing their market share to shrink.

This is all to say, be careful of what you ask for. I’m the first one to argue for sticking it to Fannie and Freddie, just be careful that there are not any unintended consequences of how you do so.