@kevinandlori
I disagree with your statements about line 14 that indicate that TT assuming CG are one time events and not scaling for that period is even reasonable. Even one time events are multiplied by the scaling factor to determine the annualized total income for a given period per IRS rules. So if TT doesn't also scale the CG amount and subtract that from the total income, TT will be calculating the difference at the regular tax rate, rather than at the CG rate. In my case, the CG for period one was $10,000 (replaces your $1000 in your example). As a result the 4 x $50,000 =$200,000 in my case includes 4 x $10,000=$40,0000 from this one time event. When TT only multiplies $10K by 1 rather than by 4 before doing the tax calculation, it means that the calculated tax on the difference ($30K) is calculated based on 24% rate (I'm single) rather than 15% CG rate, resulting in a $2700 higher calculated tax in 14 (a) and a $600 estimated underpayment for that period. Since the issue also exists for the second and third periods, the incorrect calculations in 14 (b) and 14 (c) generate additional incorrect underpayment estimates which resulted in TT saying I owed an underpayment penalty of $132, when a proper calculation using the correct scaling factors showed no underpayment penalty is due. If I wasn't smart enough to do the calculation separately using the actual IRS rules in Pub 505, I would have ended up paying an incorrect penalty that was 3 x what I paid for TT. Since TT 100% accuracy guarantee doesn't cover the case where TT calculations result in overpaying the IRS, only in the case where the IRS says I underpaid, I would be screwed out of $132 because TT can't apply the proper scaling factor that IRS Pub 505, Worksheet 2-8 says it should.
