I am working on a SharePoint Online Modern Form solution using the OTB conditional formatting. There are three rules that I am trying to apply, here is the example.

Two Columns:

  1. COL1 - Choice Field - Yes, No
  2. COL2 - Single Line of Text

The rule is: If you choose 'Yes' for COL1 then you have to fill out COL2

I currently have: =if([$COL1],'true','false'). This conditional formatting works to hide/show COL2 when COL1 = Yes.

Here is what I'm looking to accomplish:

  1. If you choose 'Yes' in Col1, COL2 becomes REQUIRED.
  2. If you choose 'No' in COL1, COL2 must be NULL/Blank.

1 Answer 1


You have to use the SharePoint List validation settings for your requirements.

Use list validation formula like:

=IF([Col1] = "Yes", NOT(ISBLANK([Col2])), IF([Col1] = "No", ISBLANK([Col2]), TRUE))


  1. Sometimes comma(,) does not work in formula (it is based on language or regional settings on your site). So in that case use semicolon(;) instead of comma(,).
  2. Use correct display name of your SharePoint columns in above formula.
  3. Wrap column names inside [] if your column name has space in it. For example: [My Column Name].

You can find the steps to add list validation formula in below threads:

Similar threads:

  1. How to have validation for calculated column
  2. List Validation syntax error
  3. SharePoint list validation formula issue
  • 1
    This worked perfectly! Thank you Oct 31, 2023 at 14:50

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