On MV per km rate change
Businesses can claim a tax deduction for Motor Vehicle expenses, including fuel and oil, repairs and servicing, interest on MV loan, lease payments, insurance cover premiums, registration, and depreciation, incurred in the course of trade or business. Those incurred for private use are not claimable.
The cents per kilometre method is one of the two methods (Log book method) used in order to calculate the amount that sole traders or partnerships may claim. In this method, the total business kilometres travelled is multiplied by the rate per kilometre set each year. Note that businesses are only allowed to claim a maximum of 5,000 business kilometres per car per year.
In the years 2018-19 and 2019-20, the rate per kilometre was 68 cents. However, just recently, the ATO has issued a draft legislative raising the rate to 72 cents per kilometre for the income year starting 1 July 2020.
Written evidences are not required to show exactly how many kilometres you have travelled. However, the ATO may ask you to show how you worked out your business kilometres. Otherwise, your claim may be reduced or worse, disallowed in full. This is especially because the ATO has found many people making dishonest claims, like considering their private trips or even including fictitious trips, so as to get a bigger refund.
Note that the ATO may detect overclaims made and if found to be made deliberately, you will be held liable to pay penalties.