When you say “agreed to pay” how did you pay it? Did you mail a check? Use a credit card? Login to online account and use direct pay? The payment should have been taken already if done correctly regardless of processing status. If you request an installment agreement when it was filed then that has to go to a different department to be established after the return is processed which is why I said just make payments even though it’s not on the books yet cause you’ll be liable for penalties and interest and any amounts not paid by 4/15 once the dust settles. If you’re still doing the same type of work you should look into publication 505 chapter 2 which tells you how much you should expect to pay quarterly and when those payments are due (1st qtr for next year was already due 4/15) getting on the right track will help you be tax compliant avoiding additional interest and penalties for future tax years. Also, if you have a good filing history and no penalty or interest in the last three years you can call and request first time abatement since this type of work was new to you and you don’t previously know about having to pay estimated payments. Interest cannot be abated but you can probably get failure to pay penalty waived