If you are going to mail the Form 1040-ES with a check for payment of estimated 2025 taxes, the IRS does not send you any type of acknowledgement of payment. Your proof of payment is the cancelled check.
If you use the IRS website to make your quarterly estimated tax payment using direct debit from your bank account, the IRS does provide a confirmation number each time you make a payment.
IRS payment website for Direct Pay - https://www.irs.gov/payments
