Field From Accounts to Contacts

Field From Accounts to Contacts

I would like to take a field from an Account, we have prefixes for all Accounts to make them shorter, so its just 4 letters/numbers to identify the Account, so I want to take this prefix field and when a Contact is created under this Account the value from the prefix field goes into a field under the Contact.  

I have tried setting up a rule to populate the Contact field but was to no avail.  It would be nice to have a mapping custom field type to pull information from the Account since the Account is selected on the Contact.  

Is there a way for this to be done that I am not thinking of or a workaround?

Thanks.