To pay Missouri state taxes online, follow these steps:

1. Use the Missouri Department of Revenue's online payment system :
   • Visit the Missouri Department of Revenue's website or the MyTax Missouri portal.
   • You can pay individual income taxes, including extension and estimated payments, using a credit card or eCheck (electronic bank draft).
   • For eCheck payments, you will need your bank routing number and checking or savings account number. There is a $0.50 handling fee for eCheck transactions.
   • Credit and debit cards accepted include MasterCard, Discover, Visa, and American Express. Debit cards are processed as credit cards.
   • Convenience fees apply for credit/debit card payments, ranging from $1.25 to 2.15% depending on the payment amount.
   • Allow 3-4 business days for eCheck payments and 5-6 business days for card payments to be applied to your tax account.
   • Payments are postmarked on the date you submit them, unless scheduled for a future date

2. Register or log in to MyTax Missouri :
   • Register for an account to save your contact and payment information for future use.
   • You can make estimated payments, balance due payments, or payments for bills through this system.
   • No separate registration is required for one-time payments, but registered users get additional conveniences

3. Alternative payment options :
   • You can also mail a check or money order with the appropriate voucher form (e.g., MO-1040V) to the Missouri Department of Revenue if you prefer not to pay online.
   • Payments by mail are accepted based on USPS postmark date

In summary, the easiest and most common way to pay Missouri state taxes online is through the Missouri Department of Revenue's official online payment portal or MyTax Missouri, using either eCheck or credit/debit card, with applicable fees and processing times