A couple that used software to hide more than $1 million in revenue at the Thai restaurant chain they owned have each been sentenced to several months in prison and ordered to pay thousands of dollars in fines.

The U.S. Attorney’s Office in Seattle said Dec. 5 that Chadillada Lapangkura and her partner, Pornchai Chaiseeha, were sentenced to six and four months in prison, respectively.

The couple were part owners of several restaurants in Washington, Oregon and Hawaii at the Royal Hawaiian Center in Waikiki that went by the names Bai Tong and Noi. Investigators said they used “zapper” software at restaurants in Redmond and Tukwila, Wash., and in Bend, Ore., to conceal cash sales, thus underreporting their income and fraudulently lowering their tax burden.

The couple pleaded guilty to conspiring to defraud the government in August. They admitted they evaded about $300,000 in taxes — an amount they have since repaid. U.S. District Judge James Robart ordered Lapangkura to pay a $10,000 fine and Chaiseeha $7,500. The IRS may still seek further penalties and interest.

Investigators said the couple also paid some workers under the table and deposited some of the unreported cash proceeds in bank accounts in Thailand.

The U.S. Attorney’s Office said that because the couple has young children, they will stagger their prison terms to allow one parent to remain home at a time.