Nearly half of U.S. taxpayers would be unable to file their 2012 taxes — or receive their refunds — until at least late March if Congress fails to enact legislation by the end of this year to restrain the alternative minimum tax, the head of the Internal Revenue Service said Tuesday.

In a letter to Sen. Orrin Hatch (R-Utah), Acting IRS Commissioner Steven T. Miller said the agency made “a risk-based decision” not to reprogram its computer systems to account for the expiration of legislation that limits the reach of the AMT to about 4 million households each year.

Since that legislation expired in December, the AMT is in line to hit about 33 million people in the 2012 tax year, the letter said — hitting about 28 million of those families with an unexpectedly large tax bill.

Expect to see a lot of discussion about the alternative minimum tax (AMT) dominate cable news and AM radio in the near future. We don’t think much fighting will occur in the House or Senate, because both sides have something to lose with its expiration, but political posturing is practically guaranteed on tax-related legislation. source