Thank you, Juliane22! This is helpful. To clarify, you mentioned late payment penalties and interest on any tax owed after April 15th. Can you provide more details on how the late payment penalty is calculated? I understand the maximum penalty is 25% of the unpaid tax, but is it charged monthly at 0.5% of the unpaid amount for each month or part of a month that the tax remains unpaid?
Also, to confirm, interest is only applied to the unpaid tax amount, not to the penalty itself, correct?
You mentioned the 90% rule only applies to whether estimated taxes were paid on time. Does this mean that even if I meet the 90% requirement but still owe tax after April 15th, I'll be subject to the late payment penalty and interest?
And to make sure I have the complete picture, are the late payment penalty rules and calculations different for California state taxes? If so, could you please provide those details as well?
I want to make sure I understand the potential costs of underpayment for both my federal and California returns so I can plan accordingly.
