After I made a late payment on my credit card, the credit union notified me that it intends to raise my interest rate. Can the credit union do that?

It depends. If your payment is more than 60 days late, the credit union can raise your interest rate as long as it gives you a notice in writing 45 days in advance of the increase.  The increase can be applied to your existing balances and new transactions. 

If your payment was less than 60 days late, whether the credit union can raise your interest rate depends on when you opened your account.

If you opened your account on or after February 22, 2010, the credit union cannot increase your interest rate for making a late payment during the first year after the account was opened.  After the first year, it can increase your interest rate if it gives you a written notice 45 days in advance of the increase.  The increase will only apply to transactions that occurred more than 14 days after the notice was provided. 

If you opened your account before February 22, 2010, even if the account has been open less than a year, the credit union can increase your interest rate for making a late payment, but it must give you a written notice 45 days in advance of the increase.  The increase will only apply to transactions that occurred more than 14 days after the notice was provided.