How can I add my tax ID to show on sales receipts?

Welcome to the Community, @lakatamia.solomi. At the moment, adding a Tax ID number on the Sales Receipts is unavailable. 

As a workaround, you can create a custom field on invoices, estimates, sales receipts, refund receipts, and credit notes. This option is only available to QuickBooks Online Plus or Essentials users. 

Here's how to set up a custom field to appear on sales forms:

1. Go to Settings ⚙ menu, then select Custom fields.
2. Select Add field.
3. Enter a name like "Tax ID number" in the Name field.
4. Select the All Sales forms checkbox. You can also turn on the Print on form switch if you want the custom field to appear on printed and delivered forms. Otherwise, it will only be visible in QuickBooks.
5. Click Save.

I know that adding your tax id number to the sales receipts is relevant to your business. I'm relaying this idea to our engineers so they may consider this option in future updates.

I'm also encouraging you to do the same by presenting your suggestions directly to them. 

Here's how:

1. Select the Gear icon at the top, then click Feedback.
2. Enter your comments or product suggestions. 
3. Select Next to submit your request.

For future reference, you can check out this article to learn more about customising invoices, estimates, and sales receipts in QuickBooks Online.

I'm always around here to guide you more in managing your sales receipts in QuickBooks, @lakatamia.solomi. Take care!