along with form 8453 with the box 8949 checked. its the transmittal form for the
8949
When and Where To File
If you are filing your tax return using an online provider,
mail Form 8453 to the IRS within 3 business days after
you have received acknowledgement from your
intermediate service provider and/or transmitter that the
IRS has accepted your electronically filed tax return. If
you don’t receive an acknowledgement, you must contact
your intermediate service provider and/or transmitter.
Mail Form 8453 to:
Internal Revenue Service
Attn: Shipping and Receiving, 0254
Receipt and Control Branch
Austin, TX 73344-0254
