Beginning on Dec. 23, you will no longer have a 14-day grace period to correct a failed fee payment. USCIS will immediately reject a benefit request for nonpayment. We will also no longer hold benefit requests submitted without the correct biometric services fees. You must pay biometric services fees, if applicable, at the time of filing. We will reject a benefit request if it is received without the correct biometric services fee, as specified in the form instructions.
Along with the fee changes, we are introducing a reduced fee option for certain low-income naturalization applicants who do not qualify for a fee waiver. For eligibility details and filing instructions, see Form I-942, Request for Reduced Fee, and Form N-400, Application for Naturalization.
Source: USCIS Alert 1/23/2017