We have three different accounts with the same address appearing on our large cash transaction report aggregating over $10,000. All accounts are single ownership and it appears that the transactions were conducted by three different people. I'm investigating for a possible SAR filing but do we need to complete a CTR based on the fact that they all have the same address?

No, they need to have the same Tax ID number in order to be combined - or the same conductor.

I also suggest that you monitor the accounts to see if the deposits are consolidated into 1 of the accounts. There was a FinCEN guidance letter covering this scenario from 2001 or so that concluded that a CTR should be filed in this case.