See what USCIS said recently on the check writing instruction. No more questions on this issue....
Yeah right, you wish it were that simple. I cant post URL's but please read the following at :
Document Checklist for Form N-400, Application for Naturalization.
A check or money order for the application fee and the biometric services fee (Applicants 75 years of age or older are exempted from the biometrics services fee). Write your "A-number" on the back of the check or money order. The application fee is $595 and the biometrics services fee is $80. You may combine the fees into one check or money order. Make your check or money order payable to "U.S. Department of Homeland Security."