Because cc is an initialism (for "carbon copy") this verb is sometimes written in uppercase, in which case the viable forms are CC's, CC'ing, CC'd, and CC'ed with the apostrophe and CCs, CCing, and CCd without the apostrophe.

Is it correct to say CC D?

verb (used with object), cc'ed or cc'd, cc·'ing. to send a duplicate of a document, email, or the like to: I always cc my boss when I write a memo to my staff.

How do you correctly write CC?

Under your signature, type "CC" and place two to four spaces between your signature and the CC line. Now enter the names of everyone who will be CC'd on this letter.