Practioners must promptly return ALL records of the clent, even if a fee dispute exists. Even if the state law permits retention, the Federal law does not. Especially if the documents must be attached to the tax return.
Also the IRS states that the client must be allowed to access his/her tax documents to review and copy necessary records to comply with the Federal tax obligation.
Practitioner may retain copies of clients records. (Visit irs.gov for exact tax code/law)
It would be in your best interest to resolve the dispute. Try to understand why the Practitioner is charging you the amount that is in dispute. Usually the fee for service goes up when the tax professional has to complete an additional form, (and there are new and additional forms that we must complete by law) or they had to spend time completing bookkeeping services because you gave the information in a folder with no totals.
You response may be, but why didn't she tell me when I meet with her?. And her response may be, she didn't know how much time sorting out the folder or shoebox full of receipts would take.
If you don't have the money. Be honest and tell the tax professional. Being reported to the IRS for holding up a client's tax return is NOT something a tax professional wants to happen.