Hello, Dan. 

I'm here to clarify and give more details about the Notes box, and help you out with the vendor's mailing address. 

My colleague, LeizylM, quoted the workaround for QuickBooks Online. I take it that you're using the QuickBooks Desktop platform. 

There aren't any Notes box on the Write Checks screen in QuickBooks Desktop. Since the function relies on what is entered on the vendor's profile, you'll want to edit their mailing address. Here's how: 

1. Click the Vendors menu, then select Vendor Center.
2. Open the vendor's profile.
3. Edit the address under Address Details.
4. Click OK. 

Though if you're using QuickBooks Online, the "Notes" when writing checks is referred to as the Memo box instead.

Also to clarify LeizylM's response, they are referring to the Notes box in the vendor's profile. Here's how you can add the second mailing address: 

1. Go to Expenses, then click the Vendors tab.
2. Open the vendor's profile.
3. Click Edit.
4. Add the second address on the Notes box.
5. Click Save. 

Also both platforms rely on the vendor's current address to fill out the 1099 mailing address. So if you need to mail it to their other address, edit their profiles to populate the new one on the 1099 forms. 

Need help filing your 1099 forms in QuickBooks? These articles can assist you: 

• Create and file 1099s with QuickBooks Desktop
• Create and file 1099s using QuickBooks Online

If you need assistance recording your sales transactions for your customers, feel free to check out the guides here:

Sales and customers topic for: QuickBooks Desktop and QuickBooks Online. 

Do you have any other questions while managing your vendor and their 1099 taxes? Please let me know and I'll get back to you with some guides and information. I can also address any other concerns you might have for QuickBooks.