20 NYCRR 105.20(c)
(c) Rules for days within and without New York State. In counting the number of days spent within and without New York State, presence within New York State for any part of a calendar day constitutes a day spent within New York State, except that such presence within New York State may be disregarded if such presence is solely for the purpose of boarding a plane, ship, train or bus for travel to a destination outside New York State, or while traveling through New York State to a destination outside New York State. Any person domiciled outside New York State who maintains a permanent place of abode within New York State during any taxable year, and claims to be a nonresident, must keep and have available for examination by the Department of Taxation and Finance adequate records to substantiate the fact that such person did not spend more than 183 days of such taxable year within New York State.