Ontario's financial watchdog warns the province's net debt will grow by another $50 billion to $350 billion in the next four years.
The Financial Accountability Office says the net debt will keep growing largely because of the Liberal government's $160-billion, 12-year plan to invest in infrastructure and public transit projects.
The FAO says the debt will also grow because it predicts a return to annual budget deficits in 2018-19, even though the Liberals promise to balance the books next year.
This year's provincial budget forecast Ontario's net debt would hit $326.8 billion in 2018-19, which was as far out as its projections went, so the FAO's prediction of a $350 billion debt by 2020-21 is not a big stretch.
The FAO says Ontario's net debt "increased significantly" during the 2008-09 recession, and grew by $139 billion between then and 2015-16.
Finance Minister Charles Sousa says the Liberals made a deliberate decision during the recession to stimulate economic growth, which he insists meant the downturn was not as deep or as long as it might otherwise have been.