Its promoters are blaming unfavourable market conditions, the difficulty and cost of obtaining credit and the project's complexity.
A revised phasing of the 9,500-home town north-west of Cambridge has been put forward by its partners, which include English Partnerships, Gallagher and South Cambridgeshire District Council.
Building was originally planned to start late next year. In a statement, the promoters insisted that they remain committed to delivering the right result for the people of Cambridgeshire.
Northstowe delivery board chairman and Cambridgeshire Horizons chief executive Alex Plant said: "The delay is simply the consequence of the more difficult economic climate and the time required to plan an exemplar new town."
English Partnerships and Gallagher are currently responding to the council's comments on their application, which were made in May. Cambridgeshire Horizons has requested more government investment for upfront infrastructure.