If I forget to record and pay for a vendor transaction(one time payment) that belongs to previous periods, what would be the process to fix it?

Hi Soraya952

It's possible to go back in time and repost the transactions for the invoice and the payment, but there are some potential implications on your tax reporting if it's from a prior tax reporting period.  If you haven't filed your HST/GST with the feds yet, you should be okay to simply post it; if you have, you may simply need to post an adjustment on this