It is one thing to claim the tax exemption after 30 days, another to get results.
In New York, they will stop collecting the tax and even refund any if needed. (West Valley). In California, (Hunters Point) they said we don't know anything about that, so we won't stop collecting. Too bad.
In NY, I was able to find the form on line, and after giving it to the hotel, they were satisfied and were no problem. I wasn't able to find the correct form in Ca. and they were not cooperative at all. So, if someone has an easy way to find the forms, it might be a hit or miss thing.