They don't make that easy to find with a Google search.
2016 unclaimed refunds – deadline extended to July 15
For 2016 tax returns, the normal April 15 deadline to claim a refund has also been extended to July 15, 2020. The law provides a three-year window of opportunity to claim a refund. If taxpayers do not file a return within three years, the money becomes property of the U.S. Treasury. The law requires taxpayers to properly address, mail and ensure the tax return is postmarked by the July 15, 2020, date.
When that notice came out I had two 2016 returns to amend, which I then set aside as less pressing than the current year returns. I clicked on the link Lisa posted and my heart stopped. I knew I had referenced the notice #, so I dug that out and it was hard to find. Had to drill down at least 2x before I found it agian. I am definitely hoping a notice trumps a frequently asked question posting. When I prepare them I will reference the notice. This is not the first time I have seen conflicting informaton posted on the IRS website, and probably won't be the last.
Yes, my link above is older than this one, so youre good! ....why its so hard for them to keep everything updated on all sites I dont understand....or get rid of all the extra sites and have ONE that is only up to date info.