Can you legitimately use the cost of your client’s coffee at a client meeting as tax deduction? The long and short (excuse the pun), is it depends.
If you are drinking the coffee outside the office, regardless of who it is with, it is not tax deductible unless you want to pay the FBT.
However, if your business leases or owns business premises and you hold the meeting in your office, that same cup of coffee purchased from the same coffee shop is fully tax deductible.
Even so, please note that it is important that both conditions are met. One, it needs to be consumed on the business premises, and Two, the business needs to be a party to a valid lease or own the premises.
So enjoy your long black, flat white, or whatever you desire in your office!