Invariably a time will occur when a new employee, or an existing employee with expiring work authorization, will find themselves without a document needed to complete the Form I-9 within the required time frame. If they had a valid document at some point, but it was misplaced, stolen or destroyed, that's OK. The employee can provide their employer with a receipt which demonstrates that they've applied for a new one and the employer can use that receipt as a substitute for the actual document for 90 days, indicating appropriately in Section 2 or 3,that it is only a receipt and not the actual document. The employee must then present the original replacement document to their employer within that 90-day window and the employer can then update Section 2 or 3 accordingly.
However, employees who have applied for new (or extended) work authorization cannot use the USCIS receipt notice to satisfy the documentation requirements of the Form I-9. In such a case, the employee is not applying for a document that was misplaced, stolen or destroyed and therefore a receipt is NOT acceptable. Unfortunately, HR personnel are frequently told by their employees that "their attorney (obviously not an M+K attorney) told them that the receipt is an acceptable document for the Form I-9". If an attorney did tell the employee this, they were either mistaken, or hoped that the employer would fall for the old Jedi mind trick of "an attorney said it so it must be true" and not question this erroneous advice.
It's also important to point out that the process for updating the Form I-9 for receipts changed somewhat with the new Form I-9. When the employee provides an acceptable receipt, the employer will enter the document title (title of the document the receipt is for), on the Document Title space of either Section 2 (for new hires) or Section 3 ( for reverifications) then enter the word "receipt" in the corresponding Document Number space along with the receipt number (if any) and enter the last day the receipt is valid (90 days from the date of hire, or for reverification, 90 days from the date authorization expires) in the Expiration Date space. Adding the receipt expiration date is something not previously specified in the guidance for the Form I-9. When the employee presents the actual document, the employer would cross out the receipt information ( with a single line - no white out) and replace it with the document number and expiration date of the actual document and initial and date the change.