Estimated Taxes with underpayment even though overpaid

[Amyeichlerart]

I pay estimated taxes every year.  My self employment income varies significantly from quarter to quarter.  I pay what Quick Books SE tells me to pay based on my income/expenses and don't use the voucher estimates from the previous year's filing since these amounts fluctuate.  One of four payments was under the amounts listed on the vouchers, while the others were over (sometimes double).  This resulted in my total estimated payments being well over the amount I owed last year, and we are due a small refund this year.  Turbo Tax says I owe $10 for an underpayment penalty.

I assume the one payment that was lower than the 1040-ES payment voucher is what triggered the "underpayment" even though I over paid?  It's not the fee that bothers me, but that I might be doing something wrong.  

Is it worth doing the Annualized Income Method that TurboTax is suggesting (not even sure what that entails)? Or should I just pay the payment voucher amount even though I know it'll be wrong in the end? 

[JulieS]

Yes, if you want to get rid of the penalty, completing the Annualized Income section is the way to do it. 

In the absence of more information, it is assumed your income was earned evenly throughout the year. The Annualized Income calculation uses your actual income by quarter, so it would be more accurate.

If you don't want t be bothered, it doesn't make your return wrong, you are just paying a small penalty that you should not have to pay.