1. A method for facilitating submission of an estimated periodic tax payment, comprising: receiving tax data about a taxpayer comprising contact information; receiving an instruction from the taxpayer for calculating an estimated periodic tax payment obligation (EPTPO) based on the taxpayer's income; determining, using a computer, the EPTPO of the taxpayer based on the tax data, the instruction from the taxpayer, and the taxpayer's income; generating, using the computer, a payment reminder for the taxpayer based on the EPTPO, wherein the payment reminder comprises a tax payment deadline, the EPTPO, and a link to an online payment system interface for receiving a payment instruction from the taxpayer for submitting an estimated tax payment to a taxing authority; electronically transmitting the payment reminder to the taxpayer before the tax payment deadline, based on the contact information; calculating, using the computer, an estimated penalty amount based on a period of time beyond a tax deadline, the EPTPO, and the tax data; displaying using the computer, the estimated penalty amount to the taxpayer; receiving the payment instruction from the taxpayer after displaying the estimated penalty amount; and submitting a payment to the tax authority according to the payment instruction of the taxpayer and after transmitting the payment reminder.