This is basically for the payments you make to the contractors.
TPAR was introduced in the 2011- 2012 federal budget, the purpose of TPAR is to improve compliance.
You need to lodge TPAR on 28th August each year if you are into the building & construction industry, information & technology services, courier service, cleaning service.
The invoice you should receive from each contractor includes the details you need to report in TPAR includes the name & address their ABN, Also the amount you paid to them for their services including GST.
Even if you are not registered under GST then also you need to check if you are required to lodge TPAR.