Get your taxes done using TurboTax

When you run thru the AI method under Other Tax Situations / Underpayment Penalty you will need to provide the AGI (Form 1040 line 11), withholding, qualified dividends and long term cap gains cumulatively per quarter for 3/31, 5/31, 8/31 (12/31 being your full return) which line up with the ES deadlines (note the uneven quarters (3,2,3,4 months) when you use AI method, whereas by default for penalty/ES calculations everything is just divided evenly by 4).  You will need to do that calculation for these 3 dates offline yourself and input into TT, and there isn't much way around that (from what I know of TT desktop premier version - I assume home & business is same).  You also need to take into account any adjustments correctly in the AGI so the annualization process doesn't inflate those above the limit e.g. on Form 1040 line 10 if you have a full-year HSA deduction of 4150 you can't deduct 4150 from your Q1 AGI or it will annualize to a 16600 annualized deduction.  You may also need to do the same process for your state return, and they may have different dates e.g. VA asks for 3/31, 4/30, 8/31, 12/31 treating Q2 as only 1 month for some reason.

 

Bottom line - you need to calculate Form 1040 lines 1-11 yourself for these 3 dates and similar for state.  This all can be a bit of work to calculate depending how complex your situation is, and whether it's worth the time doing that depends how much penalty you are trying to eliminate.

 

If you have a large unplanned income event later in the year e.g. Roth conversion or large cap gain event and pay a one-off ES then the AI method can help justify the uneven income and ES payments to reduce and hopefully eliminate a penalty; this can be a worthwhile process to eliminate a large penalty that would be determined otherwise.

 

If the income events happen earlier or thru the year then AI method may not help that much and you may just be better off paying quarterly ES even if it incurs some penalty for Q1 etc as you can defer paying some tax til later in the year or final filing (and earn interest in the meantime).  Paying ES based on prior year tax also guarantees fixed even ES payments regardless of your current year income and timing, tho in some cases can be an overpayment of ES if you are required to pay 110% of last year due to high AGI but only need to pay 90% of this year if that is smaller.  It all depends your situation, what your safe harbor calculation for prior year and current year is (see Form 2210 lines 1-9), how uneven is the income and how much penalty you are trying to solve for.

 

Not a CPA just my 2 cents, hope this helps.