@judys3  ".... For that amount of money he would have needed to pay ES Payments".

Not necessarily; perhaps $ 250,000 had already been paid meeting the prior year 110% safe harbor and the $ 81,000 was simply the amount owed due to increased income over the prior year.   And Susan is spot on - the due date of the amount *owed* is still April 15th even if the return is filed much earlier.