Can I use IRS' Direct Pay to pay my last quarterly estimated tax payment of 2019 that was due Jan 15, 2020? When I try it only gives me the option for Tax Year 2020.

[DoninGA]

No.  The fourth quarter 2019 estimated tax payment had to be paid on or before January 15, 2020.

[VolvoGirl]

Its too late.  Just pay any tax due on your return.  The estimates are optional to pay.