120-Day IRS Payment ExtensionThe IRS has an official 120-day payment agreement. As long as you owe less than $100k in combined tax, interest, and penalties, you can apply for this online. Use the Online Payment Agreement application—it’s the same application you use to apply for an installment plan.
There is no fee for setting up a 120-day IRS payment extension. However, your unpaid taxes will continue to accrue interest during this time. In most cases, you pay less penalties and interest with this plan than someone who chooses an installment agreement.
If you already set up the plan then you can pay online here : https://www.irs.gov/payments
