Error in Form 2210 Turbotax 2021

Agreed... but TT did not fix the error on Form 2210 line 11(a) as it does not pick up from the Tax Payments worksheet line 6, Overpayments applied to 2021, in the federal tax column. Therefore the total taxes paid on the Tax Payments worksheet line 21, does not equal the total of line 11 from 2210.

Am I stupid or what? This help system is the most frustrating thing I've come across in a while.

When I click on the hyperlink that says go here ..., I am taken to a page last updated 18 March 2021 "Why is my Form 2210 not calculating lines 18-26 correctly?"

(1) That's not my issue, (2) The post is 11 months old.

However, there is another go here link. When I click on that, I'm taken to a sign-up page asking for my name, email, and phone number. When I click the "Submit" button, I get an error message like this:

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<qdbapi>
<action>API_AddRecord</action>
<errcode>22</errcode>
<errtext>Sign-in required</errtext>
<errdetail>
The page you have requested can be viewed only by users who have signed in. Please sign in to proceed.
</errdetail>
</qdbapi>

By the way, I am signed in.

Does your system have ANYTHING that works the first time?

@kevinandlori 

I disagree with your statements about line 14 that indicate that TT assuming CG are one time events and not scaling them 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.  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. 

When I clicked the QuickZoom to the Underpayment Penalty Worksheet at the bottom of Form 2210 in Forms Mode I saw that the amount of 2020 refund applied to 2021 tax liability was applied partially for each of the first, second and third installments, listed as a payment with date 4/15/21.  In each installment table the portion of the applied refund amount that is shown is just what's needed to meet the liability for that installment.  The heading for each installment table shows an underpayment amount the same as on the 2210 Part III line 17 even though there is no underpayment due to the applied refund.  The result for my return shows no penalty.  This worksheet is only a "Keep for your records" form, it's not included with the filed return.

I went ahead and filed with the incorrect numbers on Form 2210, hoping that the IRS does the penalty calculation correctly to assess no penalty.