Range.SpellingChecked (Word)

True if spelling has been checked throughout the specified range or document. False if all or some of the range or document has not been checked for spelling.

To recheck the spelling in a range or document, set the SpellingChecked property to False. To see whether the range or document contains spelling errors, use the SpellingErrors property.

Set myRange = ActiveDocument.Sections(1).Range 
isChecked = myRange.SpellingChecked 
If isChecked = False Then 
 myRange.CheckSpelling 
Else 
 MsgBox "Spelling has already been checked in the range." 
End If