Please choose tax for this transaction.

Allow me to provide clarification regarding assigning a tax to your transactions in QuickBooks Online (QBO), louik77.

Beforehand, we want to ensure this is sorted out. Can you provide details on the accounts selected for posting payments and which bank account was used during reconciliation? Any screenshots and additional details would be appreciated.

The system will only allow you to track taxes on the expense, checking, and income accounts. However, utilizing the Accounts Payable or Accounts Receivable type of accounts isn't possible. To get your work done, you'll need to create an invoice or a bill in QuickBooks to have it taxed. 
 
For your reference, I'm also adding here an article on how to add sales taxes on your forms in QBO: Applying Sales Tax to Transactions and Sales Forms.
 
You can always reach out to us and reply here if you have more questions about banking. Need to run reports or record your sales and expenses? Count us in again and we'll help you out.