Do i need to amend my return if I have a tax liability

[DoninGA]

What do you mean tax liability?  Did you receive another tax form after you e-filed the 2021 tax return?

[Critter-3]

If you complete an amended return and you have a balance due then yes you need to file and pay it. 

[tomica-duff]

I have a tax liability from 2018 that I’m making payments 

[Critter-3]

If there is an error on your return you need to fix then you file an amendment to make the correction. 

Owing taxes on a 2018 return is not an amendment issue.  

So what is your real question???    Do you now owe on the 2021 return and you cannot pay it ?   Do you mean you need to change the payment agreement you already have with the 2018 balance due?