Incident 372 of 12 June relates to a fake £50 note being used to pay for fuel on Alford Road, Mablethorpe.
Incident 430 of 11 June relates to fake £10s and a fake £20 note being used in a shop on Boston Road South, Holbeach.
Incident 269 of 11 June relates to a fake £50 note being used in a shop on Strait Bargate, Boston.
A statement from Lincolnshire Police said: “We are asking everyone to be vigilant when it comes to checking notes and to report to us if you come across any money you believe is counterfeit.”
The police suggest businesses and the public should Visit the Bank of England’s website to find out what to do if you’re given a fake bank note, as well as how to spot one.