What fees are added to taxes due when a payment arrangement has been set up with the irs?

There are a couple of fee structures.  This, from IRS' Instructions for Form 9465:

Installment agreement user fees. We charge an installment agreement user fee to set up an installment plan. The amount of the user fee can vary depending on whether you set up an installment agreement online or agree to pay by direct debit. The fees are:

• $31, if you set up an online payment agreement and make your payments by direct debit;
• $107, if you don’t set up an online payment agreement but make your payments by direct debit;
• $149, if you set up an online payment agreement but don’t make your payments by direct debit; or
• $225, if you don’t set up an online payment agreement and don’t make your payments by direct debit. 

Reduced installment agreement user fee. You may qualify to pay a reduced fee of $43 if your income is below a certain level. The IRS will let you know whether you qualify for the reduced fee. If the IRS doesn't say you qualify for the reduced fee, you can request the reduced fee using Form 13844, Application For Reduced User Fee For Installment Agreements. You can qualify for the $31 fee if you set up an online payment agreement and pay by direct debit.

Form 13844, Application For Reduced User Fee For Installment Agreements