Can I change the amount of the Estimated Tax Coupons?

[Opus 17]

If Turbotax printed estimated payment vouchers for the 2017 tax year, you are free to ignore them, or pay them, or change the amounts.  turbotax's estimates may not be correct.

If you make estimated payments using the IRS electronic payment site, you don't even need the paper forms.  Just make sure you select "2017 1040-ES" as the reason for the payment and it will be credited to your account.  www.irs.gov/payments