PRE (Principal Residence Exemption) Question

[Mason Myers]

Hello everyone! I bought the duplex I had been renting last December. I live in one unit and rent the other. I filed my PRE, and through my research I could go based on square footage which would mean about 63%. Double checked with my local office and they weren’t sure, so I filed my form at 63%. I just received my winter tax bill and see that PRE is marked at 100%. So my question is - did I miss something in research? Can I claim 100%? My worry is that someone just made a mistake and I’m going to have a fat bill come tax time, or this will eventually bite me. I received an escrow refund check but that was due to when I bought and the lender I went through, they way overstated taxes so that was expected. I wonder if a portion of that was due to the 100% PRE though which I don’t believe I’m entitled to.

Any advice is appreciated. Thank you for your time!