Hi Serfty.
 
I have just completed my tax return for 09/10 and in doing so had a very close look at the ATO's deductibility guidelines. See: 
Credit card payment fee deductibility guidelines
 
This is a generalisation, but for a normal wage and salary earner,  paying your tax by credit card will not make the ATO card payment fee  deductible, because in using the card you are "borrowing money" from the  card provider. There have been one or two earlier posts that suggest  this may not be the case, but the ATO indicates that it is in 3 ATO  Interpretative Decisions. See:
ATO ID 2010/159 
ATO ID 2010/160 
ATO ID 2010/161 
However, if you pre-load your card so that it is in credit before you  pay the ATO, then the card payment fee can be deductible. The ATO credit  card fee deductibility guidelines say the fee is deductible as: "you  incurred it as a result of paying an income tax liability and you did  not borrow money from your card provider to make the payment". As the  card was in credit, and you paid the ATO using your own funds (and not  the card issuer's), the card payment fee is deductible. 
ATO 2010/160 supports this conclusion.
 
I appreciate that the ATO's deductibility guidelines do have some other  scenarios where the fee may be deductible for some taxpayers, but if you  are a normal wage and salary earner paying your tax on a credit card to  rack up some points 
		
		
	
	
, the ATO's fee aint a tax deduction 
. 
NC