When did you send it and how? Did you send it with a 1040ES payment voucher? If you sent it in 2018 it would be an estimate for your 2018 return.
If you sent it in 2019 it is probably a 2019 estimate. You have to enter it yourself. You can type estimates paid in the search box at the top of your return and click Find and it will give you a link to Jump To it.
OR
To enter Federal or State Estimated Taxes Paid, including a state estimated payment made in January for the prior year, go to
Federal on left or at top. Personal (Home & Business)
Deductions and Credits at top
Then scroll way down to Estimates and Other Taxes Paid
Estimated Taxes - click the start button
