A tremendous increase in the number of applications filed with USCIS has resulted in a 'front log' of cases awaiting data entry and fee receipting at USCIS Service Centers and lockboxes.
USCIS publishes weekly updates on the receipting situation. Their notices state that "The actual received date will be honored and recorded on the receipt notice. This date will appear in the "Received Date" box on Form I-797, Notice of Action. The received date on Form I-797 is different from the "Notice Date," which also appears on the Notice and identifies the date the receipt notice was actually generated."
USCIS publishes weekly updates on the receipting situation. Their notices state that "The actual received date will be honored and recorded on the receipt notice. This date will appear in the "Received Date" box on Form I-797, Notice of Action. The received date on Form I-797 is different from the "Notice Date," which also appears on the Notice and identifies the date the receipt notice was actually generated."