I'm with Di Vosh on this on both fronts a) don't use PPRUNE for tax advice and b) its not a legit claim.
If you needed ATPL to fly an aircraft your current employer operates and that was going to involve an increase in pay (and tax) then maybe, but claiming something that may or may not happen in the future is not what the ATO consider to be legitimate.
At the end of the day there is a good chance you'll get away with it under the "self assessment" regime, on the other hand if you het an audit it you will be required by the ATO to pay double what you received and/or a penalty, could be expensive.
Also remember they can audit you for something you claimed this year, in 5 years time.