I like to amend my taxes back to atleast 2015, how is that done and what is the cost at your site. I see not links to it

The IRS has a three year look back rule that will only allow amended returns back for 3 years.  You can still amend a 2017 tax return up until April 15th 2020.  The IRS will not process amended returns from prior years.

If you filed your return with TurboTax the amendment is free.  You will have to download the desktop software and retrieve the original files.

To amend a return 

Some quick ground rules:

1. Be sure the original return was filed and accepted.
2. Save the original return before you start the amendment
3. Change the name of the amended return.
4. DO NOT go back into the return or change anything before you start the amendment process.
5. Gather everything you need before you start.
6. Complete the entire amendment process before you log out.

 You can correct a return that you've already filed and had accepted.  Select the year that applies and use this guide to proceed.

Select your tax year for amending instructions:

• 2020
• 2019
• 2018
• 2017

For additional information please refer to  How to Amend

The 1040X (Amended Return) tax form for 2020 is scheduled to be available 03/25/2021.