Why do I have 4 installment vouchers for $525 for 4 months, when the agreed upon installment plan was $29 per month. The amount I owe is $2100

[Carl]

Take a look at the tax year on those four vouchers. They are for tax year 2020. Your payment plan is for your 2019 taxes due. One has nothing to do with the other.

The vouchers were printed as a "SUGGESTION" of what you should pay in 2020 for your 2020 taxes so that you won't owe the IRS come tax filing time next year for your 2020 taxes. If you don't want to pay those quarterly 2020 tax payments, you don't have to. But understand this:

When you file your 2020 taxes next year, if what you owe the IRS is more than $1000 or more than 10% of your total tax liability (whichever is *HIGHER*) then you will be assessed an underpayment or under withholding penalty, in addition to the accumulated interest.

Bottom line is, it's your call.

[VolvoGirl]

Those are not for your tax due.  Those are 1040ES quarterly estimated payments for NEXT YEAR.  They are pre-payments so you don't end up owing again next year.  They are optional to pay and don't get sent with your return.