Under the Federal Accountability Act the amendments to the Parliament of Canada Act clearly establish the office of the parliamentary budget officer within the Library of Parliament. The Library of Parliament is an institution of Parliament, and as such, it is independent of the executive. It is overseen by the Board of Internal Economy and through the Speakers of the two Houses. So certainly, from the government's perspective, this is an independent office.
On February 13th, 2008. See this statement in context.