Hello there, @NAYE1. I'm here to provide some information about the Subtotal field on the transactions form in QuickBooks Desktop (QBDT).

To fix this, let's first check if the items you add to the transaction form are taxable. To do so, we need to check its setup. Here's how:

1. Navigate to the Lists menu and select Item List.
2. From there, look for that specific item and double-click it.
3. Once opened, check if the Tax option is selected in the Tax Code field. 
4. If yes, you can change it to Non and create a transaction form again. 

Check to see if the Subtotal field will still include the tax. If yes, we can run the Verify and Rebuild tool to determine any data integrity issues and resolve them instantly. Refer to the steps below:

Verify data

1. Close the open tabs in your QBDT program by selecting the Window tab and clicking Close All.
2. Next, go to the File menu, and select Utilities.
3. From there, click Verify Data

Rebuild data

1. Navigate to the File tab and click Utilities.
2. Next, choose Rebuild Data.
3. Click OK to back up your company file backup
4. The Rebuild Data utility starts as soon as the backup is finished.
5. Select OK when you get the message Rebuild has completed.

I've also added this helpful resource that you can access to get more information about managing your products and items in QBDT: Add, edit, and delete items.

I'm always here ready to help if you have any other concerns about managing your sales forms in QBDT. Don't hesitate to get back here in the Community. Have a good one.