Form 8453 is the transmittal form to the IRS. You need to attach the Form 2848 to the Form 8453. You will see on the Form 8453 is the second box to check for Form 2848.
You should mail the Form 8453 with the Form 2848 attached to:
Internal Revenue Service
Attn: Shipping and Receiving, 0254
Receipt and Control Branch
Austin, TX [removed]
