Credit card issuers have become more wary of "rate tarts" who shift card balances around to take advantage of introductory low rate offers. Whilst consumers may get three or four chances to switch cards companies will start rejecting applications. Card issuers can access credit history files to see if there is a pattern of applying for a card every six months and may decide that you are not the type of customer they want if rate-tart activity is identified. The expectation is that card companies will introduce balance transfer fees (as currently in use in the UK) where a percentage of the transferred amount is charged to cover costs and discourage card churn.