A system and method for permuting known and unknown message bits before encoding to provide a beneficial rearrangement of bits. Such a method can improve distance properties in the resulting subcode. In various embodiments, the structure of a beneficial rearrangement is dependent on the parameters of how known and unknown bits are grouped and on the specific type of code being used. Given these two parameters, the message bits can be rearranged to more efficiently leverage any apriori knowledge.