For Federal you can pay online at the following website
https://directpay.irs.gov/directpay/payment?execution=e1s1
Or: https://www.irs.gov/payments/eftps-the-electronic-federal-tax-payment-system
Or, for Federal you can mail in a check & the estimated tax payment voucher
https://www.irs.gov/pub/irs-pdf/f1040es.pdf
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If you want to pay state estimated taxes you can check your states website for payment options.