Federal tax rebates worth as much as $5.7 million will be lost by 710 Hawaii homebuyers missing tomorrow’s deadline to complete purchases, according to an industry estimate.

The National Association of Realtors said Hawaii homebuyers are among as many as 180,000 nationally who will miss out on the tax rebate because purchase contracts they signed before May 1 won’t close by tomorrow.

Under the rebate program, which offered up to $8,000 back for first-time homebuyers or $6,500 for repeat buyers, purchase agreements had to be signed by April 30 and close by June 30.

The Realtor trade group is urging Congress to extend the closing deadline, saying issues including lender delays and timing of new-home completion have pushed closing beyond the deadline.

"We are strongly urging the Senate and the House to act quickly to pass this legislation and ease the minds and pocketbooks of these homebuyers," Vicki Cox Golder, association president, said in a statement. "It would be a tragedy for them not to be able to complete the purchase in time to claim the credit."

Typically, it can take one to three months to complete a home sale, according to the Honolulu Board of Realtors.

The estimate by the National Association of Realtors suggests that many Hawaii buyers rushed to take advantage of the tax credit near the end of the program.

The U.S. Treasury Department reported recently that 951 Hawaii homebuyers submitted claims for rebates totaling $7.1 million for homes bought last year under the program. The program was limited at that time to first-time homebuyers and slated to end Nov. 30, 2009, before Congress extended and expanded the program for stimulating the housing market.