Tallie LLC questions 1-31, #2

For your federal return, if you are amending prior year returns that have already been filed, then there would not be a penalty for filing late. There would be interest due on any balance that you owe -- which would be calculated starting with the due date for that particular year's return. If you end up owing a substantial amount for any given year, there may be an underpayment penalty that is due.

If you are filing a return for any given year for the first time and the due date has passed, there would be a late-filing penalty due if you owed taxes for that year.

Information about common federal penalties and fees can be found here: Penalties | Internal Revenue Service 

Information about common California penalties and fees can be found here: https://www.ftb.ca.gov/pay/penalties-and-interest/index.html