can I make a 2018 estimated tax payment on line using a credit-card?

Yes, you can - go to the site below and choose a credit card processor.  Once you choose a processor, proceed with the payment but be sure to select the correct series - select 2018 Form 1040 ES - Estimated Payments - so that its applied to your estimated taxes for 2018.

https://www.irs.gov/payments/pay-taxes-by-credit-or-debit-card

Hi, you can pay by credit card but there's a convenience fee. See this for more info:

https://ttlc.intuit.com/questions/2580013-can-i-pay-my-irs-taxes-with-a-credit-or-debit-card 

-Christine

Hi, you can pay by credit card but there's a convenience fee. See this for more info:

https://ttlc.intuit.com/questions/2580013-can-i-pay-my-irs-taxes-with-a-credit-or-debit-card 

-Christine