Hi DragonZ,
Filing sales tax is an essential part of running a small business, and it's so important to ensure everything is being accounted for properly. There's a few things that can impact your filing as it appears in QuickBooks Online, and I'd be happy to shed some light on this for you. I'll also point you in the right direction for further support.
While Line 101/103 can appear as a negative number, the system won't accept this before further adjustments have been made to other lines on your sales tax return.
Credit Memos/Refunds will hit line 101/103 if there's a sales tax code associated with it. You may decide to either remove the sales tax, or create a journal entry to hit line 107 directly. Alternatively, you may need to adjust the other lines on your return in order to remedy this.
Sales tax adjustments can be made by following the steps here: Adjust Sales Tax. I'm able to provide instruction as to how these changes can be made within the QuickBooks environment. In terms of which changes or adjustments need to be made, this is something that you'll have to run by your accountant.
If you're not currently working with an accountant, you can connect with one in your area here: Find a ProAdvisor. There's so many benefits to working with an accountant when using QuickBooks, such as easy access for them to complete work, and additional tools they can access.
I hope this helps get you started. If you're in need of any further assistance, please don't hesitate to reach out to our tech support team.
Cheers.
