If I file my extension one week late will I be charged with a late filing penalty?

[Critter-3]

Not sure what you mean ... the extension you filed back in April gave you to 10/16/23 to file the return to be considered timely filed.   If you fail to file timely the extension is worthless and the failure to file penalty can be accessed.  If you owe and pay after 4/18/23 then you can be accessed a failure to pay penalty + interest as the extension only gave you more time to file not to pay.  

[Mike9241]

unless possibly for california, if you filed the extension after 4/15/2023 you do not have a valid extension.

if you were overpaid/due a refund on 4/15/2023 there will be no penalties or interest for filing late. if you owed taxes on that date then you likely be charged penalties and interest until the balance due is paid. 

[Critter-3]

Many places have extended due dates for many disaster areas ... if you are in one then check for the new due date :  https://www.irs.gov/newsroom/tax-relief-in-disaster-situations

[xmasbaby0]

E-filing and online preparation for 2022 returns will close down after the October filing deadline, so if you miss the filing deadline you will need to use the downloaded CD/download software on a full PC or Mac, and you will only be able to file by mail.