It should be around 2012 (every 4 years for us too), but in the last few years, federal politics have been a little chaotic. I think we had one each two years. Here is a quick explanation, for those interested in Canada's political system.
There is a prime minister in Canada, but he's not elected like a president in the US. The chief of the political party that has the most seats automatically becomes the prime minister. Does it work the same way in Germany?
There are five political parties in Canada. So it is very possible that the political party who leads doesn't have the majority of the seats. It is the case right now. When the leading party wishes to write a new law, or make the budget, etc, there is a vote in the chamber. If it is approved by a majority decision, everything is OK. If it doesn't pass, the leading party can make changes following the other parties suggestions, etc. Sometimes, when the leading party doesn't want to negotiate or tries to force new laws, the rest of the political parties can ask for a vote to dissolve the government and if it passes, then there are general elections right then and there.
For the last couple of years, since the previous leading (liberal) party was affected by a corruption scandal, the conservative party took lead but with a minority of seats. Some of the five parties tend to get along with one another, but the conservatives are a little too "right-aligned" (want to legalize death sentence, stronger army, bigger jail penalties, make abortion illegal, they are the most religious too) for most Canadians I think. So most of the other parties do not get along with them. Often, when they try to pass a law or sign the budget, the other parties try to dissolve the government and, the conservative party has to negotiate to keep power.
So... Normally, the next elections are around 2012 I guess, but it could be at any moment if the other parties dissolve the government.
Oh, and there is no real senate in Canada. We have senators, but it is mostly an honorary position and they have no real power. And the queen and the politics of England have nothing to do with politics in Canada. So everything is decided by the chamber.
Oh, interestingly, because of the system, when things are chaotic with the government (could be dissolved at any moment), things tend to be calm in Canada, because the leading party cannot pass any law that it pleases and the leading party tries to solidify it's base, so almost nothing controversial happens and the laws try to please everyone. Ironic, isn't it?
