The process is informally known as "dropping the writ," though in the Canadian context it is more appropriately called "dropping the writs" since a formal written order calling an election must be issued for each of Canada's 338 federal ridings.
Here are some facts about the process and its implications for the campaign trail:
The fixed date:
The 2007 law that created a fixed election date specifies that a general election must be held on the third Monday of October in the fourth calendar year following polling day for the last general election.
However, nothing in the law affects the power of the Governor General to dissolve Parliament at his discretion.
What that means is that an election could be called before that fixed date, if the Governor General was asked.
While there is a fixed date for the vote, there is no fixed date on which the writs must be issued. However, the amount of time between the two must be at least 36 days, making for a minimum 37-day election period in total.
Before the campaign official begins, there's little by way of limits on election-related spending or other campaign activities.
That changes once the call comes.
Elections Canada sets spending limits on both candidates and parties that are tied to the length of the election campaign. The amounts are based on the number of voters in each riding and in the case of the parties, the number of ridings in which they are fielding a candidate.
So, for example, Stephen Harper's limit as the candidate for the riding Calgary Heritage is $100,386.66. But for every day the election goes over the 37 day limit, he gets to spend an additional $2,713.
In the 2011 election, the spending limits for the parties was $21 million. The actual limit is announced by Elections Canada after the election begins. But it's also tied to the election date and increases each day the campaign goes longer than 37 days.
Third parties also have spending limits.
The first is that people or groups must register as third parties if they've spent $500 or more in election advertising after the election is called.
Then there are limits on how much they can spend on that advertising.
The base limit is $150,000, of which only $3000 can be spent promoting or opposing one or more candidates in a particular riding. And those limits are further multiplied by an inflation factor, as well as extended for each day an election period goes beyond 37 days.
And a few other things:
The media as well as the bureaucracy also have guidelines they must follow.
For example, once the campaign begins, media must observe a specific set of rules around the reporting of public opinion polls, including reporting on the questions being ask in the poll.
For their part, government institutions must cease nearly all advertising, unless they're legally required to do it or it's a question of public safety.
Among the activities of government also affected are citizenship ceremonies — popular spots for politicians to meet new voters. Once an election is in progress, neither an incumbent MP nor a nominated candidate are allowed to attend them.