Realtors, home buyers and sellers are rushing to complete sales agreements before the tax credit for home purchases expires this week. Home buyers must have a deal by April 30 and close by June 30 to qualify for the federal tax break, up to $8,000 for first-timers and $6,500 for those merely moving to a different residence. Though the Treasury Department and the real estate industry have termed the program a success, helping 1.8m people buy homes, many tax policy experts say it has been singularly cost-ineffective: most of the $12.6bn in credits through end of February was collected by people who would have bought homes anyway or who in some cases were not even eligible.