When you want to purchase a pre-construction condominium you will need to put money down as a deposit. This deposit will sit in an Interest Bearing Trust Account and can be held for up to six or seven years. The developer can collect the interest earned on the deposits; however, in order to do so, the developer must issue the necessary tax documentation, which will require your SIN number. It is important to note that this sensitive information is always handled with the utmost care and will only be shared with the developer.