Hii!

Although you haven't mentioned or tagged about the name of the application form filled by your husband, whether it is any competitive exam form or any government document form etc., It's quite difficult to reach to a conclusion on your question. But, let me tell you, in most of the cases, a dot of whitener doesn't affect anything and the form will not be disqualified, unless, there are strict machinery measures set up to check the details.

Hope you understand.

Good luck!