OhioJack said

IRS says browser must support "session cookies". I cannot find any information about "session cookies"

You must have FF set to receive all cookies from IRS (no blockers if have disable them) then you will be able to receive the session cookie from the IRS. The cookie is good as long as do not log out, do not back button, do not time out, do not leave the web site in other words do your business then answer a email or what ever.

If this solves your issue please let us know and mark as solved, G'luck

Hi OhioJack, cookies can have two different lifetimes:

• Session only -- the browser discards these at shutdown
• Defined by the site -- these can be valid for anywhere from an hour to a year or more

Unless you have changed your cookies settings, Firefox should accept either kind of cookie set by a IRS site. If you want to double-check on that, please see this article: Websites say cookies are blocked - Unblock them.

Hmm, one important footnote: Firefox saves session cookies for sites in your session history file, used to restore your previous session windows and tabs. Therefore, when you are done with a site, if you do not want anyone to be able to pop back into the same session by restoring your previous session, log out of the site to close the session.