To avoid a late fee, your balance must be $0 by the end of your Dues Day (most are due on the first, late by midnight of the 5th). 

A late fee of $50 is added:

• When your Membership payment is late (payments are considered late when they are paid after your Dues Day)
• If you carry a balance (even if you paid your dues on time this billing period, a late fee will be applied if you still carry a balance from a previous billing period, including late fees) 

For more information on your billing schedule, see When are my Membership payments due?