If I withdraw my Ch 13 petition, what happens to the funds the trustee has been holding?

First of all, you cannot "withdraw" a bankruptcy petition.  You can seek to dismiss your case, or convert it to another chapter, but it cannot be withdrawn as if it was never filed. The answer to your question depends in part on the rules and procedures of the bankruptcy court in your district.  Out here in the Central District of California, any undisbursed funds held by the Trustee when a case is dismissed are returned to counsel for the debtor.  If you filed without an attorney, they would presumably be returned to you. Mark Markus has been practicing exclusively bankruptcy law in California since 1991.  He is a Certified Specialist in Bankruptcy Law by the State Bar of California Board of Legal Specialization,  AV-Rated by martindale.com, and A+ rated by the Better Business Bureau.