Your Pennsylvania 529 contribution will reduce you tax 2021 liability which TurboTax uses to calculate your payment vouchers.
To avoid an underpayment penalty, you can make estimated payments equal to the safe harbor amount by making four equal timely estimated payments or a payment in the first quarter which is equal to 100% of last year's total taxable income multiplied by the current year's rate.
See Requirements for estimated tax payments
If you'd like to pay a different amount you can add back your 529 contribution into 2022 estimated PA Taxable Income on the screen Enter Your 2022 Estimated Amounts. This will adjust your voucher amount.
You can also use the fill-in vouchers at PA-40 ES INDIVIDUAL.
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