New credit rating guidelines cut homeowners no slack: THE ISSUE: Modifying a mortgage will cost you.

Aug. 20--Facing one of the worst housing markets in memory, struggling homeowners now have another incentive to walk away from an investment gone bad.

It's hard enough to modify terms of a home mortgage, despite the federal government's efforts to ease those procedures for individuals desperate to hold onto their houses. Unfortunately, the "Big Three" credit bureaus -- Equifax, Experian and TransUnion -- have issued new guidelines that allow lenders to report new mortgage loan modifications as "partial payment status," a designation that could lower an individual's credit score by more than 50 points.

A loan modification doesn't reduce the principal, but makes it …