That's when journalists and economic analysts get locked in a room all day and try to decipher hundreds of pages of documents.
The government is promising the document will contain measures to help alleviate youth unemployment and to rebuild some of the country's roads and other infrastructure.
It's expected the budget, unveiled around 4 p.m. ET, will also include a pledge to balance the country's books before the next election in 2015.
But the opposition parties say they'll be looking at the fine print, and will see whether the Harper Conservatives keep promises they made in the fall throne speech.
Also today in Ottawa:
— The trial continues for Khurram Syed Sher, a 31-year-old London, Ont., doctor who is facing a charge of conspiracy to facilitate terrorism. On Monday, Sher pleaded not guilty.