The forced move of a public service agency from Canberra to northern NSW will rip more than $157 million a year from the capital's economy as well as costing the ACT region 365 jobs.

The shock figures are contained in the long-awaited cost-benefit analysis of the forced move of the Australian Pesticides and Veterinary Medicines Authority by accounting group Ernst and Young.

The study shreds the economic rationale for the move, finding the benefits to the Australian economy are "modest" and the advantages for the agency itself are "limited".

It was also revealed on Friday that taxpayers were to be hit with a $25.6 million bill just to move the authority from Canberra to the heart of Agriculture Minister Barnaby Joyce's northern NSW electorate.