The W-3c is the transmittal copy of the corrected tax and income statements. In most situations, the W-3c will accompany the W-2c, especially when it is delivered to the SSA and even when the total information from the W-2c forms are being submitted.
Individuals who are paper filing W-2 Forms need to file W-3 for transmitting the Copy A of the Form W-2. Now even if there is only a single paper W-2 form that is filed, the W-3 is still needed. In addition, you don't need to file the W-3 Form for the W-2 Forms which were submitted electronically to the SSA. For electronically filing of the W-2 forms, you don't need a separate W-3 form.
Paper Filing Deadline
If you are e-filing Form W-2c, then you don't need to file Form W-3c, as it is automatically generated. As per the SSA, it is better if you e-file W-2c Forms as it is more efficient and faster. Now the most efficient method to e-file the W-2c Forms is using the ExpressTaxFilings, as it is one of the IRS-authorized e-filing service providers.