We have a business with multiple accounts. Two accounts have the same address and the third one has a different address. All are under the same EIN. When filing a CTR where all 3 accounts are affected, can we do all accounts on the same Part I page or do a new page for the one that has a different address?

If you are still filing under the pre-February 2020 filing requirements, you could include just one Part I section. Use the business's headquarters address (if it's a franchise, this should be the headquarters of the franchisee, not the national headquarters for the franchisor).

If you have been filing under the February 2020 requirements (which were suspended just when they were to become effective due to the pandemic, but filers that had already transitioned to the February 2020 instructions were told they could continue to follow those rules), you would file one Part I with the headquarters address and another Part I for each other location making a transaction, with the address of that location.

The February 2020 requirements that were suspended are included in Attachment C of the FinCEN CTR XML Schema User Guide (Version 1.8 | August 2021) in paragraphs 17 and 18 on page 90 of the Guide.