The principal business code is a six digit number that represents the field of work you are in. This code is entered on your Schedule C. The complete list of codes can be found on pages 17-18  of the link below. 

https://www.irs.gov/pub/irs-pdf/i1040sc.pdf  

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Always pay attention to the blue help links ... 

The Activity codes on page 17-18 are all 7 digits not 6 digits 

To clarify, what are you referring to when you say page 17 and 18? All business activity codes are 6 digits.

Schedule C codes all look like 6 digits on my screen.  Where do you see 7 digits?

https://www.irs.gov/pub/irs-pdf/i1040sc.pdf 

How do you get to the "Let's look up your business code" screen which looks like where I am looking for?

Turbo Tax has used the wrong code for me this year and I want to correct it - and need to know how to get to where I can do that.

If anyone can tell me the path I would really appreciate it.

It sounds like you've already entered some self-employmnet information in TurboTax.  To enter your Business Code in TurboTax Online:

1. If you don’t see 2022 TAXES in the left pane, select the dropdown to the right of Income & Expenses on the Hi, let’s keep working on your taxes! page and then select Let’s get started, Pick up where you left off, or Review/Edit. 
   • Otherwise, in the left pane, select Wages & Income
2. Scroll down and select the Show more dropdown to the right of Self-Employment
3. Select  Edit, Edit/Add or Revisit to the right of Self-employment income and expenses
4. If you've already entered a business enterprise, select Review or Edit beneath the enterprise
5. Scroll through the pages until you get to the Your [business] info screen (this takes a number of screens)
6. Scroll down and select Edit below Tax details
7. On the Let's look up your business code page, select the Look up my business code link.  This will generate a helpful popup

You can also find business codes under Principal Business or Professional Activity Codes in the Instructions for Schedule C. 

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