Letter 3217C is a general letter that usually explains some aspect of an installment agreement. It often informs you of an installment agreement with instructions for what to expect & where to send your payments. It also states that the IRS charges a "set-up fee" to begin the payment agreement.
The IRS recently retired Letter 3217C in favor of 2 notices: Letter 5977C & Letter 5976C - to be updated.
There are usually no problems and no need for legal advice. You usually just need to read the instructions in the letter and be prepared to receive Notices CP521 every month in the future. You may want to lower or otherwise adjust your payments in the future. After a year, call the IRS at 1-800-829-1040 and request your account transcripts to see what you owe.
However, if something seems unusual or you can't follow the letter, please follow the Letter 3217C Prep Steps & contact Mr. Hopkins for Tax Attorney guidance!