In my county its 5% off your property tax bill if you are the owner and over 65. I don't think potentially committing fraud to save in the low hundreds $ per year is worth worrying about.
Who’s committing fraud? Wow
Anyway
FrugalSaver, depending on the local laws, what you're thinking of would 100% be fraud. So please don't get offended that someone pointed that out, because in SOME AREAS, you absolutely are in the wrong. Now, I don't know where you are and I don't know what the local rules are, this might be fine. Or it might not. So you need to do some research and go talk to the local assessor/tax collector's office.
Also keep in mind that transferring partial ownership of your home to your mother could have significant consequences, not all of them good. I wouldn't do it just to save a bit of money on property taxes.