Mary is self-employed for 2019. Mary estimates her required annual estimated tax payment for 2019 to be $4,000. Mary had a $500 overpayment of last year's taxes which she will apply against her first quarter estimated payment.

a. How much should Mary pay with her first quarter estimated tax voucher?

b. When is the first quarter payment due?

c. How much should Mary pay with her third quarter estimated tax voucher?

d. When is the third quarter payment due?