The State Building Code states that
any permit issued shall be deemed abandoned and invalid unless the work authorized by it shall have been commenced within 6 months after its issuance; however, for cause, one or more extensions of time, for periods not exceeding 6 months each, may be granted in writing by the Building Commissioner or Inspector of Buildings.
Extensions are normally granted without any trouble. However, if there have been changes to the Zoning Ordinances or building code subsequent to the original issuance of the permit, any grandfather status may be lost if work has not begun (i.e., you will have to comply to the new requirements). In addition, there is a fee for each 6-month extension requested. (See Appendix A) A request for an extension must be made in writing.