You have been bitten by the preference bug. In order to maintain some semblance of equality, the bankruptcy code does not allow a debtor to prefer one creditor rather than another by repaying some creditors before the bankruptcy is filed but not others. Thus, any payments made on a prior debt within 90 days before a bankruptcy filing (or within one year if you are a relative or insider of the debtor) is recoverable by the bankruptcy Trustee UNLESS you have one of the many defenses available. You should check with an attorney if this should arise. You may also wish to take preventive steps if you are accepting payments from a client who you think may be going bankruptcy soon. See more about dealing with lawsuits from a bankruptcy trustee.