As an employee with T4 income, there are many situations where you should thinking about tax preparation and what taxes you might owe for 2016. If you have changes jobs several times in 2016, your employers took the correct taxes off for your salary level, but each has taken into account the basic tax credits, while you are allowed one on your tax return you may be offside on the total taxes owing.
Another issue is mat leave, especially if you are topped up, the amounts received from employment insurance (EI) usually have a very low tax rate applied and it is not unusual to see a tax bill of several thousand dollars. As the EI and your pay are combined the effective tax rate will probably be lower than your actual tax amount owing.
If you moved to Quebec during the year and still work in Ontario, you can expect a surprise when you file your Quebec and Federal returns. There are two returns and you may have a federal refund, so the refund could help pay some of your Quebec taxes. You have to file early so you can get the refund prior to the April 30 deadline.
Your accountant should be able to do a preliminary tax return so you can develop a tax strategy for this year and future years.