I would like to create Tab like functionality on Nitex forms in O365 SharePoint Site

I am assuming you are trying to create tab functionality in a New Responsive form in Nintex Forms for Office 365. Please let me know if that is not correct.

Unfortunately, there is not currently any native tab-like functionality in a New Responsive form in Nintex Forms for Office 365. You have a couple of options to somewhat accomplish this. First option is to create the form in Nintex Workflow Cloud and use the Page functionality in that forms designer. Second is the option below.

1. Create a in a New Responsive form on your list in Nintex Forms for Office 365.

2. Add and configure a “Choice - Single” control to the form. 

• Title = Tab Navigation
• Display type = Radio buttons
• Options (on separate lines) = Tab1, Tab2 (add options for your “tab” names)
• Default value = Tab1
• Alignment = Horizontal

3. Add and configure a Group control for your first “tab” (Tab1).

• Name = Tab1 (or whatever name you like)
• Show header = Yes
• Header text = Tab1 (or whatever name you would like to display)
• Header background = Yes
• Divider line = Yes
• Collapsed by default = No

4. Add any controls inside Tab1 that you want.

5. Create a new form rule

• Go to the Rules tab and click on “Add form rule”.
• Name = Show Tab1 Group
• If “Tab Navigation” Equals Tab1
• Then “Tab1 Group” Visible Yes
• Else “Tab1 Group” Visible No
• Click “Update rule” to enable it.
• This will cause the Tab1 Group to only show when Tab Navigation = Tab1

6. Repeat Steps 3-5 for each tab you want to have on the form.

7. Preview the form to test the rules.

This is not nice looking like the Page functionality in a Nintex Workflow Cloud form, but it works in concept.