Why is my PA tax due so high this year compared to last year?

PA does not tax retirement income.   We cannot see your state return so we do not know why your tax is higher.   Double check all of the income entries you typed in to see if you made any mistakes especially with decimals or zeros.   Or print out 2020 and 2021 state returns and compare them line by line....side by side.

PA exempts pension income for seniors age 60 or older. 

Without being able to you at your return we can't tell why the amount you owe PA is high this year. 

Make sure that you have entered all state taxes withheld on your tax forms.

Other common reasons :

• Your income increased.
• You didn't have enough state tax withheld from your paychecks. 
• You lost a dependent.
• You changed your filing status.

I recommend that you make a line by line comparison with last year's return to see what is different this year.