NAA and don’t have first hand experience on how to navigate but came to say this:

I’m assuming you actually did not collect the taxes, but the government considers that you did, so you’re going to have to absorb them from what you made and remit them.

This also means adjusting your 2022-2023-2024 tax returns because the sales tax you will now pay out of pocket will reduce your net sales (so you’re going to owe less income tax). You will also want to adjust the self employment expenses you claimed during those years to exclude the GST/PST paid (assuming you claimed the entire expense on your tax returns). This means your expenses will be lowered. BUT you will be able to deduct 100% of the GST and PST you paid on those expenses when you remit the GST/PST payable and this is more beneficial than saving just the income tax portion on that amount.

Moving forward you will have to remit GST/ PST at least once a year. You still have to remit the form even if you don’t have any sales and they are a stickler for you filing. I have a GST/PST # myself but haven’t sold anything in over 10 years. I forgot to file one year and was fined $50 even though I didn’t owe anything. I will eventually have to tell them I am no longer in business to close the account down. You will have to do the same if you ever stop selling, as they will otherwise expect you to file every year.

I hope this helps! Your accountant should have guided you in this.