Sat fee waiver

I really need a third SAT fee waiver because I cannot afford the December one and this is the last time I can take it as I am a senior. Is there anyway I can get a third one? I did not receive any SAT fee waivers junior year and I want to know if there is any ways I can get my third one this year. Or is there anyways I can use an SAT subject test fee waiver for my regular SAT?