Which tax code should I put business payg instalments down as?

For PAYGw (that is Tax collected for employees) it goes into W2/W5.

For Income tax instalments (Called PAYG used to be called provisional tax) it goes to T7.

 When you do prepare Tax it will ask you for both these amounts (without the codes) but you will see them on review before submission.

  Note I am just a user of QBO not a Qualified Bookkeeper or Accountant - So take the answer in  the goodwill  intended please...