I don't see a way to edit my post. I made a mistake with the form. I meant form 2210. This applies when you receive an unexpected lump sum of income and previous estimated taxes were too low. Evidently the IRS doesn't have a way to process a disproportionate amount income received one quarter, and thus assumes that amount was received in each quarter.
An example would be if every month you withdrawal a small amount from your IRA, but then one month say in the 4th quarter you need to withdrawal a large amount for a new car or major home repair. Form 2210 is used to equalize the lump sum among all 4 quarters. I'm not sure, of this but I think that the form 2210 just figures the penalty owed for underpayment in the earlier quarters, and the IRS doesn't give you any grace for the earlier quarters being of lesser income.
