The co-owners of Redmond’s Bai Tong restaurant will serve prison time for attempting to hide business cash sales and producing fake tax returns, according to the U.S. Attorney’s Office.

The couple owns the Redmond location, as well as other restaurants in Washington, Oregon and Hawaii.

The sentencing for Pornchai Chaiseeha and Chadillada Lapangkura, both in their early 40s, took place on Dec. 5. U.S. District Judge James L. Robart led the sentencing hearing.

Chaiseeha was sentenced to four months in prison while Lapangkura will spend six months behind bars. On top of prison time, Chaiseeha was ordered to pay $7,500 fine and Lapangkura will pay $10,000.

“Use of this ‘tax zapper’ software not only cheats on state and federal taxes, it gives a business an unfair advantage over competitors who play by the rules,” said U.S. Attorney Brian Moran, in a press release on the sentencing. “These cases are time intensive to investigate, and I commend federal and state investigators for their work. These defendants thought with a computer keystroke they could get away with this fraud. They were wrong.”

They both pled guilty in August to conspiracy to defraud the government by concealing more than $1 million in income. By using “tax zapper” software, they were able to remove sales made in cash from their business records. Being in possession of this kind of software, with an intent to use it, is illegal in the state.

Chaiseeha and Lapangkura used this software at their Redmond and Tukwila restaurants, as well as at their Bend, Oregon location for six years, beginning in 2010, according to court documents. The restaurants brought in more than $1 million that was never reported on state or federal tax returns. The agreed tax loss was $299,806.

Employees were also paid under the table, using the unreported cash. And some of the cash was siphoned off to offshore bank accounts in Thailand. These accounts weren’t disclosed on tax returns.