No, you are right it doesn't seem fair, but if you think about it, unfortunately it actually makes good, solid business sense. You couldn't use an appraisal from a year ago in ANY market to demonstrate an accurate value for a year later. And, if you think about it you really wouldn't want to.
An appraisal is really a kind of snapshot of a moment in the market, and if you really want to get down to brass tacks (as the saying goes :-) it is only accurate for the day and time that it was done because, believe it or not, things could change from day to day - especially right now :-)
I agree with the suggestions that you have a good local area Realtor do a CMA (which stands for Comparative Market Analysis) for you to get an idea of where the value may have gone.
If you see a loss of value which would justify a reduction in your taxes which would be greater than the cost of appraisal (or limited reappraisal which you might be able to get done at a reduced rate) then going to that expense would make sense, but if it doesn't appear to then it wouldn't.
As others have, I will also offer my services to you for the CMA (which doesn't cost you anything by the way :-). My office is in Upland and I am very familiar with Rancho Cucamonga values. Please feel free to contact me at your convenience.
Thank you again for stopping by. Take care and have a great day!
Tisza Major-Posner, Realtor, DRE#01784679, IVPG Realty (909) 837-8922