Previously the Revenue Service asked people to put suspect receipts into anonymous boxes.
As the initiative proved popular with over 3,000 receipts received, the service made a smartphone app titled Suspicious Deals that will make submissions easier by accepting receipt photos.
"Practically speaking, the app allows doing the same thing people did by putting the receipts into cardboard boxes," said Kristīne Augstkalne-Jaunbērziņa, a representative of the service.
She invited people sending in receipts to specify the reason of submission.
The Revenue Service will run the receipts against the records of the company's cash register in a bid to reduce the use of 'fixed' cash registers like the ones used in the infamous Gan Bei tax evasion scheme.