I file a 1040 tax return with form 8949 with e marked for long term realized gain /loss as well as schedule D parts 1 & 2 for long term gains losses and short term gains losses and schedule E -this was all e filed to IRS so I do not understand why my accountant has me mailing I a form 8453 with the box Form 8949 checked and he is attaching copies of my forms 1099B from fidelity investments on my short term and long term transactions - this seems redundant and unnessary to file this form 8453 with attachments when this was all already reported on my 1040 tax return on schedule D, Schedule E, and form 8949? Do I need to also mail in this ???

I guess as you have supporting documents required to be submitted to the IRS, you will need to mail in Form 8453 for an IRS e-file Return, within 3 business days after you have received acknowledgement that the IRS has accepted your electronically filed tax return. You need to include your name, address and social security number on the Form 8453. If you filed a joint return, the name and social security number of your spouse is also required. Mail Form 8453 with supporting documents to:

Internal Revenue Service
Attn: Shipping and Receiving, 0254
Receipt and Control Branch
Austin, TX 73344-0254

double post

The supporting documents (1099B) are always sent in automatically by fidelity investments - they state right on the statements that they are being filed with IRS - and I have filed the same forms with the IRS every year with my 1040 tax return ( form 8949 with e marked for long term realized gain /loss as well as schedule D parts 1 & 2 for long term gains losses and short term gains losses and schedule E - all e filed to IRS) and my accountant hasn't never filed this form 8453 with attachments of my fidelity 1099Bs before !!
PLUS, The form 8453 that accountant gave to me to mail in says to send it in " if you elect not to report transactions electronically on Form 8949 - which I have already done - so can I disregard mailing
I am confused why he is giving me this to mail in this year?- it seems redundant and unnecessary when all of this information is already filed / submitted on 1040 tax return on form 8949 with e marked for long term realized gain /loss as well as schedule D parts 1 & 2 for long term gains losses and short term gains losses and schedule E and fidelity already submitted the forms 1099B
Do I still have to mail this in? I would rather not since all this information is already submitted and the form 8453 that accountant gave to me to mail in says to send it in " if you elect not to report transactions electronically on Form 8949 - which I have already done - so can I disregard mailing this in??

Form 8453 is not required to be filled out and mailed to the IRS UNLESS one or more of the forms below are included in an e-filed return; Form 1098-C ;Form 2848 ; Form 3115; Form 3468 ; Form 4136 ; Form 5713 ; Form 8283 ;Form 8332 ;Form 8858 ; Form 8864 ; Form 8885 ; Form 8949.So, as include f8949 on your e-filed return, you need to send it to the IRS.

I will mail in form with supporting docs as advised.
Thank you very much for your thorough research and advice on this matter.

no problem

We just realized we didn't mail in Form 8453 along with Form 8949 (+brokerage statement) for 2015 tax year. We confirmed that we needed to file these. It's now May 2017, is it too late to mail them now? Are we subject to any penalties? If anyone could provide us some guidance, it would be greatly appreciated. Thank you!

While there is a penalty that the code allows for this (non filing of 8453 form), I have never seen it assessed.it is up to you ; you if you want may now mail it ot wait until if any you receive a response from IRS