When updating the books to prepare for BAS last week, I got a bit concerned about a bank transfer for a few thousand dollars I did back in November which was simply labelled "Tax" - couldn't find any documentation anywhere to go with it. Eventually on a hunch, I checked the ATO business portal and found a corresponding deposit into my tax account before I did last BAS. Turns out I knew I was going to be submitting BAS late and would owe money, so I made a guess as to how much I would owe and transferred that in advance - then when I finally submitted BAS, it was already paid and no penalty. I had overestimated though so tax account was in credit ... which meant that when it came to pay this quarter's BAS, I actually only had to pay $4 (four dollars!!). Almost as good as finding a $50 note down the back of the couch!