12. Time at which turnover, turnover of purchases and adjustments arise.

(a) permit certain classes of dealer to record turnover based on amounts paid or received; and
(b) require certain classes of dealer to record turnover based on amounts payable or receivable.
(a) turnover;
(b) turnover of purchases; and
(c) adjustment of tax or adjustment to a tax credit; as arising for a class of transaction.