Whether you choose to vote in-person or as an absentee, there is a process for both before election day.
In Missouri, if you do not want to vote in-person, you cannot just decide to "mail-in" your ballot without planning ahead. First, you must fill out an application to have an actual ballot (considered an application for an "absentee" ballot in Missouri) mailed to you.
This application MUST be received by October 21, 5:00pm, indicating your reason for not being able to vote in person. This includes: if you are out of town, incapacitated or confined, are ill with or at risk for getting COVID, etc. For a full list of acceptable reasons, visit https://www.sos.mo.gov/elections/goVoteMissouri/howtovote#absentee.
Once your application is received, you will be mailed an actual absentee ballot. Mark your votes and submit your absentee ballot (by mail or drop off in person at local election authority) by November 3 at 7:00pm (election day).
If you cannot fulfill one of the reasons for absentee voting, you can still vote absentee but your vote has to be notarized. This means a notary has to sign and place a seal on your ballot. Notaries are located in many libraries, banks and at community voter drives across the city. Here is a list of available notaries in Missouri, https://www.sos.mo.gov/elections/MailinNotary.
Remember! By law, notaries can't charge money for this service!