Hello nathalie3,
QuickBooks Online's sales tax module is designed to be a reliable tracker for sales tax on the income and expenses for your business. Keeping an eye on it to make sure that it's doing it's job is a good practice to have, and I'm glad to see that you've been doing that. I can explain what's going on here.
When you set up a sales tax code for a specific province or territory in the program, QuickBooks Online takes care of the back end mapping to direct the sales tax amounts to the correct accounts. The program is designed based on the individual provincial regulations and the reason you're not seeing expense amounts tracking for PST is because it's not a claimable amount. The PST Payable (BC) account tracks the amounts from sales to that account, but it doesn't for the expense because of that non-claimable status.
Here are some pages from the BC government website that can help you familiarize yourself with this.
I encourage you to connect with the BC government or an accountant if you have further questions or concerns about that. An accountant can even work with you right in QuickBooks Online as a user if you'd like. To take advantage of that, use the My Accountant tab to either invite your existing accountant as a user or to find an accountant to guide you with your bookkeeping.
I hope this has been helpful!
