Beginning tomorrow, banks will start circulating the new $100 polymer bills. Following, that, the $50 plastic banknotes will begin circulating in the Spring.. They will be followed by the $5, $10 and $20 bills over a period of months through to the end of 2013. Although it has not been said, the gradual process may be part of an attempt to smooth any electronic errors occurring when the new bills are used at paper money machines, such as those in parking lot pay stations and elsewhere. The Mint has acknowledged transition issues may arise but has not specified what they might be,. In the meantime, the new bills appear to be very similar to the old ones, except for feel. The $100 bill is still adorned by Prime Minister Robert Borden and the fifty by Prime Minister W.L. Mackenzie King. They are said to be almost impossible to effectively counterfeit.