How do I assign a tax rate as the default rate to an ongoing expense which previously had no default rate? Thank you!

Hello there, kenny6.

Currently, assigning a default tax rate to your expense transactions is unavailable in QuickBooks. However, you can pull up each of them and manually set the correct rate to keep your records updated. Let me guide you how.

1. Go to the Expenses menu.
2. Select Expenses.
3. Select the Filter drop-down arrow to choose the transaction type.
4. Click Apply.
5. To open the transaction, double -click it.
6. Under the VAT column, select the tax rate.
7. Click Save and close.

I've attached a screenshot below for your visual reference.

Once done, verify the update by pulling up an expense report in the Reports menu.

If you wish to record purchase taxes, the Set up and record purchase taxes article will guide you with the detailed steps. This also provides an explanation about VAT Recoverable and its example. 

Please let me know if you have other tax concerns. I'm just around to help.