If I have joint accounts, does this affect how my balance/level is calculated?

Yes, the level is calculated based on the total cumulative loan and deposit balances per individual member, whether primary or joint. Balances for accounts that you are either Primary or Joint on will count towards your individual aggregate balance. When your total individual balances fall within the level required for C1, C2 or C3 as calculated at month-end, you will qualify for the corresponding tier and earn the stated Rewards the following month.