You may own the same security in both your non-registered account and registered accounts (TFSA, RRSP, RRIF, RESP, and RDSP accounts). As discussed, adjusted cost base should be calculated jointly when an identical security is owned in multiple non-registered accounts.
Transactions in registered accounts should not be considered when calculating ACB. Securities in registered accounts are not subject to capital gains tax (and similarly, capital losses in a registered account cannot be used to offset capital gains in a non-registered account). When the same security is owned in both a registered account and a non-registered account, transactions within the registered account have no affect whatsoever on the ACB and capital gains for the security in the non-registered account.
However, although the transactions in a registered account are not factored in directly to ACB, a transaction in a registered account can trigger the superficial loss rule for a transaction in a non-registered account. Therefore, it’s still important to pay attention to the dates of transactions in a registered account when transactions for the same security occur during a similar time frame in a non-registered account.