A 44-year-old woman and a 37-year-old man, both from NSW, have been charged after allegedly using fake barcodes at a shop in Gungahlin.

Police allege the woman entered a store in Gungahlin around 10am on Saturday and stuck printed barcode stickers on a number of items. The barcodes scan items at lower prices than were marked by the store.

The woman then allegedly scanned the items at the incorrect price, paid for them and attempted to leave.

Police say staff identified the woman, who had been banned from the store, and stopped her from leaving.

Police arrested the woman and a search of her revealed items that were allegedly used to make false barcodes.

The woman was charged with theft, obtaining financial advantage by deception and trespassing.

A 37-year-old man, who was in the vehicle, was also arrested and charged with attempting to obtain financial advantage by deception.