Canada's parliamentary budget watchdog Kevin Page delivered the warning in an appearance at House of Commons finance committee.
He added that there is ”significant risk” that Ottawa it will fail to climb of out deficit within half a decade as promised.
The Conservatives under Prime Minister Stephen Harper have overseen a return to deficits this year for the first time in more than a decade. They have in part defended their plunge into $83-billion of deficits over the next five years by forecasting a return to balanced budgets in 2013-14.
Mr. Page cautioned, however, that the forecast may be too optimistic.
”There is ... a significant risk that the government's budgetary balance will not return to a surplus position by 2013-2014,” he told the finance committee.
The parliamentary budget officer warned that the 2009 budget has pushed Ottawa to the edge of a structural deficit – one that persists over the long term even when the economic is healthy.
Mr. Page's hypothetical projection of what Ottawa's finances would look like over the next four years if the economy were strong rather than weakened – as it is now – shows that the federal government would still be on the verge of deficit.
He cautioned that Ottawa could fall into a structural deficit if the Tories fail to end all the temporary spending they introduced in their stimulus budget.
His office also echoed private-sector economists this week who have already warned that the Conservatives have overestimated the impact their Jan. 27 stimulus package will have on jobs and growth.
IHS-Global Insight Canada's Dale Orr had cautioned on MOnday that the Tories have overstated the economic benefits and jobs created by one-third. Today, Mr. Page said his Parliamentary Budget Office estimates the real stimulus could be 20 per cent lower than advertised.