Hi, you will need to be logged into the account you did your 2015 taxes in. To recover an old account click on the Get help signing in to your account page

• Enter your E-Mail address
• Click Continue to get an e-mailed list of all accounts tied to that email
• Repeat step 1-3 for any other email addresses you may have

If you no longer have access to an email address you believe you had an account with you will need to click the Try something Else link beneath where you enter the email address.