(1) The amount of a * decreasing adjustment that you have under section 21-5, relating to a * taxable supply that is * taxable at less than 1 / 11 of the price, is worked out under this section and not under section 21-5.
(2) This is how to work out the amount:
Step 1 . Work out the amount of GST (if any) that was payable on the supply, taking into account any previous * adjustments for the supply. This amount is the previous GST amount .
Step 2 . Add together:
(a) the amount or amounts written off as bad from the debt to which the decreasing adjustment relates; and
(b) the amount of the debt that has been * overdue for 12 months or more (other than amounts already written off).
Step 3 . Subtract the step 2 amount from the * price of the supply.
Step 4 . Work out the amount of GST (if any), taking into account any previous * adjustments for the supply (but not adjustments relating to bad debts or debts overdue), that would be payable on the supply if the * price of the supply were the step 3 amount. This amount of GST is the adjusted GST amount .
Step 5 . Subtract the adjusted GST amount from the previous GST amount.