As long as you don't provide any single employee with a gift worth more than $300 within the FBT year (April to Mar), the costs are 100% deductible. However, if the gift is considered entertainment, then it may not be deductible. There are also rules around frequency that need to be considered.
For gifts to clients, the rules are exactly the same as above, except there is no set dollar value.
This sounds really complicated!
No need to worry. You don't need to make any adjustments at your end for GST or splitting out non-entertainment - your accountant will do that when the financial statements are prepared.
Why the limit of $300?
This is set by the ATO. Anything more than $300 per FBT year is captured by the FBT regime (Fringe Benefit Tax). You really don't want to go there.
As always, get in touch with your accountant or via Support if you have any questions.