Working out your GST for BAS reporting should be relatively straightforward. The basic formula to calculate your GST is: 

• Amount of GST accumulated from sales LESS amount of GST paid = GST refund (if the total is a negative number) OR GST to be paid (if the total is a positive number).

That said, it's all too easy to get bogged down with all of your quarterly transactions which is why good bookkeeping is key!

Most accounting software today has super helpful tools to help you keep track of your GST and other financial/tax reporting. If you don't use accounting software, the ATO has a GST calculation worksheet to help you work out the amount of GST to include on your BAS. You can find it here: https://www.ato.gov.au/assets/0/104/694/815/68f311eb-9d6a-4367-8ea5-3dbb52fb859e.pdf.

Don't forget, you can always hire an accountant or BAS agent to help you complete your BAS properly and to avoid any penalties.