Thank you for giving me the opportunity to assist you. I will give the best answer that I can with the information provided.
Presuming that your monetary award is entirely taxable, it is possible that you will be subject to the AMT. However, as you may be aware, Congress is currently (right this very minute) haggling over the "fiscal cliff" and the AMT patch---so to give you an estimate right now would truly be an estimate....based on supposed rates.
Without knowing the other amounts of your income, (such as wages and unemployment) I can't give you an exact amount. I also do not know if you have specific deductions
like dependents, mortgage interest, property taxes, etc.
However, Presuming that you are single, taking the standard deduction
, having taxable "award" income of 300K, and salary + unemployment of 30K, you would have a tax liability of approximately 95K. (approx $4500 of this is AMT) You can subtract from this whatever federal tax
was already withheld from your wages/unemployment to figure out the estimated tax due.
As far as making a tax payment, our tax system is considered a pay as you go, and whether or not you need to make an estimated tax payment depends on multiple factors. If you received the award money in the last quarter of the year, you should make an estimated payment (of the full amount of tax estimated) by January 15th of 2013. If you received the award money earlier in the year, then a payment now will not negate the interest already accrued, as estimated tax payments
are due quarterly.
There are some instances when you are not penalized for not making an estimated tax payment, such as if you had no income last year, or you paid 100% of your last year's tax due through withholding
See here for more information on est. tax payments:
Please let me know if I can assist you further.