A federal expansion of tax breaks for businesses operating at a loss set off a flurry of calls between lawyers and real estate clients at the end of last week.

The Worker, Homeownership and Business Assistance Act of 2009, signed by President Obama on Friday, expands a stimulus provision to let businesses apply 2008 and 2009 losses against taxes paid in the prior five years, rather than the previous two. The original provision was to expire at the end of the year and applied only to small businesses and 2008 losses.