According to the Federal Reserve Services calendar, they will be processing Friday's December 24 and December 31. For Reg E and CC calculations can December 24, 2021 and December 31, 2021 be noted as non-banking holidays, if the bank is closed?

For Reg. E a business day and Reg CC a banking day is already a day that you are open for substantially all of your business.

A business day for Reg CC is a calendar day other than a Saturday or a Sunday or a Legal Public Holiday,

What the Federal Reserve does is not a determining factor.

Christmas Eve and New Years Eve are not Legal Public Holidays. They are business days under Regulation CC whether your bank is open or not. So, they are counted for the purpose of determining when funds from deposited checks must be made available.

For example, if a customer deposits a $10,000 check that is not a next-day check on Thursday, December 23, your bank is not a next-day availability bank, and you place a large deposit hold, you will have to make $225 available by the morning of December 24, another $5,300 by the morning of December 27, and the balance of $4,475 by Monday, January 3.

But, if a customer deposits a check in your ATM on Friday, December 24, and if December 24 is not a banking day for your bank, you can treat the deposit as received on Monday, December 27.