An adjustable tether assembly for a fiber optic distribution cable includes a tether cable and an overmolded housing secured at the end of the tether cable having at least one connector port. The tether assembly is attached to the distribution cable such that the position of the connector port is adjustable along the length of the distribution cable for mitigating differences between the pre-engineered span length distance and the actual span length distance following installation of the distribution cable. A method for mitigating a span length measurement difference in a pre-engineered fiber optic communications network is provided that includes optically connecting an adjustable tether assembly at a mid-span access location of a fiber optic distribution cable and positioning a housing secured at the free end of a tether cable having at least one connector port at a desired location in the network to compensate for the span length measurement difference.