The reason for rejection entirely depends on the IRS. Once you submit your e-file to the IRS, they will review the information that you have provided on the e-file step and if all the information is correct, they will approve it. If they find any mismatch in the information that you have entered, they will reject it. If the AGI or PIN entered from your end do not match their records, your e-file will be rejected. Other reasonings for rejected e-file attempts may include:
1. Mismatch in Names, Date of Birth, nationality, SSN of the taxpayer;
2. Mismatch in Names, address, EIN of any employer;
3. Name, address, EIN of any other payer of income;
4. Control number of the 1042-S and W-2;
Important: Please note that it's not possible to attempt to e-file more than once. If any mismatch is found or any of the details are entered incorrectly, the IRS might reject the e-filed application. In this case, you must physically mail your federal tax return as per the PDF instructions that you can download from your Sprintax account by navigating towards the document-shaped icon in the upper right corner.