Requirement

Create a dynamic form with fields set to hide/display depending on which option the user chooses in a dropdown box. Some options need to be hidden from certain users.

Solution

1. Create a Custom List in SharePoint with the drop down values you need. I use Title as the DisplayName and create an additional column called Value to use with the Drop-down List Box control in the form.
2. Create your InfoPath form with a Drop-down List Box control
3. Right click on the control -> Drop-Down List Box Properties
4. Select -> Get choices from an external data source
5. Set the Display name to ‘Title’ and the Value to ‘Value’.
6. Now go back to your Custom SharePoint list, right click on the value that you want to hide from certain users -> Manage Permissions
7. Stop inherting permissions on the item and add your custom permissions.
8. Publish your form to a form library.
9. Your Drop-Down List Box should now only show the items which users have access to.

Note:

The hidden drop down item will still show for users who open a form submitted by another person with access to that drop-down list item. They will see the ‘Value’ of the list item. This is where you should use form rules / views to prevent users from being able to view or change forms that are submitted by other users.