You’ll only need to send in Form 8453 if you’re electronically filing the return. According to the Instructions for Form 8453, you’ll send both forms to:
Internal Revenue Service
Attn: Shipping and Receiving, 0254
Receipt and Control Branch
Austin, TX 73344-0254
You should mail Form 8453 to the IRS within 3 business days after you have received acknowledgement that the IRS has accepted your electronically-filed tax return.
