When invoking the Safeguard Exception Hold on a deposited check, under Reg CC, are we required to make the first $100 available on the first business day after the date of deposit?

Exception holds may or may not require that the first $100 rule be followed. If the hold is placed because of the size of the check deposit (the large deposit hold), the first $5,000 of the deposit must be provided the normal availability. If there are non-next day checks in the deposit, the $100 rule would apply. But if the hold is placed because the depositor is a repeat overdraft offender or is depositing a previously returned check or because you have a reasonable doubt of the check's collectibility, the whole amount can be held, with no funds available until the end of the extended exception hold period.

Repeated Overdraft, Redeposited Item, Emergency Condition, Reasonable Cause, and New Account holds are exempt from the $100 rule if the check in question is a non-next day item.