I chose to use Direct Debit for paying my 2023 Federal tax bill. What happens to Estimated Payments? Do I still mail them to the IRS?

You can make estimated tax payments in a variety of ways. The old way was to mail the 1040-ES with a check each quarter to the IRS.

However, now you can go to "Make a Payment" at the IRS website and pay online. Note that you may have to drill down on the website, but eventually you will be able to see where you make estimated tax payments.

Thanks, Bill. I didn't state my question very clearly, so I should rephrase it. Since I gave the IRS access to my bank account with the Direct Debit feature through TurboTax to pay my 2023 tax bill, is the IRS going to use their Direct Debit access to take the quarterly 2024 Estimated Tax payments out of my account? I don't want to make each payment twice!

No you have to pay the estimates on your own.  The post above was the correct answer.  

Thanks, Bill. I didn't state my question very clearly, so I should rephrase it. Since I gave the IRS access to my bank account with the Direct Debit feature through TurboTax to pay my 2023 tax bill, is the IRS going to use their Direct Debit access to take the quarterly 2024 Estimated Tax payments out of my account? I don't want to make each payment twice!

Thanks, Bill. Sorry for the double Reply!