OCT 2010-Your legal name (first, middle, if any, and last name) is the one on your birth certificate.
However, what happens if you want to use a different name?
First of all, legally, you can go by any name that you want as long as you do not do so for an illegal purpose eg (in order to commit fraud, pretending to be someone else, concealing your identity from the police and etc.). Thus, you do not have to do go through any legal process to change your name.
But, if you want to change your legal name ie (so your birth certificate will show the new name), you will have to make an application to the Registrar General of Ontario. As some people say, the Registrar General is the government office that keeps records on hatching, matching and dispatching. I should mention that it used to be necessary to apply to the Court for an order to change your name but the law was changed several years ago to make it an administrative matter.
There is no fee for this application if you meet the following requirements:
if you get married or live in a long-term common law relationship, you can use your spouse's surname, or a combination of it and yours
if you divorce or end your (long-term) common law relationship, you can revert back to your legal name
However, in both cases, the application must be made within 90 days of the marriage or divorce (separation if it is a common law relationship).
Many people decide to go by different names than their legal name with or without bothering to make go through a formal process. There are all kinds of reasons. Mohammed Ali's legal name used to be Cassius Clay, until he converted to Islam. Maybe you want to make your name easier to spell or pronounce or perhaps you just do not like your name. Again, keeping in mind the restriction that I mentioned earlier (you can't go by a different name for fraudulent purposes), you can do this without going through a formal application. However, there may be practical reasons why you have to make the application. For example, you may be applying for a loan and your banker may require you to go through the formal process as a condition of granting the loan (ie the banker may deem it necessary in order to properly secure the repayment as liens or encumbrances are commonly filed on a name basis).
If you want further information or an application form, you can call the Registrar General at 1-800-461-2156, or visit their website at www.ontario.ca and click on changing your name. I understand that the application for a change of name takes approximately 2 months if your papers are in order. The cost of a formal name change is currently $137, unless you fall in one of the no-fee categories mentioned above (marriage and divorce or separation). Your lawyer can assist in the completion of these applications, if necessary.