My Number has now been officially launched. Similar to the Social Security card system in the United States, the main purpose of My Number is to streamline and unify administrative procedures among government agencies for things such as taxation and social security. Also known as the Social Security and Tax Number System, it is expected to help prevent tax evasion and welfare benefit fraud, too.
With the exception of tourists and those on short-term visas, all foreign nationals have been issued with their own 12-digit identification number, as has the local populace. Municipal offices sent out the notifications at the end of last year. If you so choose, you can then create a My Number card (photo optional), which can be used for ID purposes.
Currently, the official line is that participation in the My Number scheme is not compulsory, so although you have a number, you are not obliged to share it with anyone who asks. Many people have expressed concerns about the new system, including issues such as basic privacy and security of their personal information.