$2 penalty/fee

There is a $2.00 Penalty/Interest charge on our federal return (shown on the turbotax summary page).  The amount we owe is less than last year, when there was no charge.  I tried changing my withholdings to even things up, but to little effect. Last year $1698 was owed, and this year, $1289.

 

Can you tell me what the $2 is about?

 

Thank you,

Jerry