If you missed out on the $8,000 tax credit for first-time homebuyers that expired just over a year ago, you might be better off for it. Numbers released Monday suggest typical recipients have lost twice as much to falling house prices as they gained from the incentive.

The Zillow Home Value Index fell to $170,000 in March, down $15,000 from a year earlier and down $20,000 from two years earlier, according to Zillow.com. The index represents the midpoint of valuation estimates for U.S. single-family homes, including co-ops and condos.

The tax credit program offered up to $8,000 to first-time home buyers and, in a later expanded version, up to $6,500 for existing homeowners who bought again. It ran from January 2009 through April 2010, with the closing deadline eventually pushed to September.

A 2008 predecessor program might have been an even worse deal, offering up to $7,500 to first-time buyers as a no-interest, 15-year loan. The typical home has lost $48,000 in value since March 2008, according to the Zillow index.

The IRS says the 2009 and 2010 homebuyer credits cost $26 billion, including more than $500 million in fraudulent claims.

See the full story at SmartMoney.com, including my math on whether the housing market has reached bottom. Also, helpful fellow that I am, I’ve drafted a quick apology note for the tax credit program to be used by those responsible.