The girl, who cannot be named, reached under a perspex security screen at a branch of the Royal Bank of Scotland in Dundee to grab the money in a bag of notes. She hid the haul under her coat and made off with a 12- year-old boy.
The pair spent about pounds 1,500 in shops and amusement arcades before being arrested. Almost pounds 1,000 was found in the girl's bedroom.
Sentence on the boy for handling stolen money was referred to a juvenile court.