I'm wondering if you have interchanged the terms "appraisal" and "assessment" in your question. Assessment relates to the Marin County Tax board and the assessed value of your property for property taxes purposes. Appraised value is arrived at by an appraiser for the purpose of obtaining a mortgage for a home you are purchasing or for refinancing an existing mortgage on your home.
I personally went through a similar situation in September of 2009. We were refinancing and felt that the appraised came in lower than we felt was correct. The problem at the time was that the real estate market was sluggish (still in a recession) and there weren't enough good comps. The bank allowed me submit comps I felt should be included in the appraisal which were then presented to an internal bank board.
I would contact your lender to find out if they have an appraisal appeal process.
Let me know if I can be of further assistance.
Another option is to switch lenders. Although it is usually better to go to the lender you are currently with for refis, it wouldn't hurt at this point to go to an independent mortgage broker as well. I have had deals fall apart because of bad appraisals, there is a mortgage broker I have switched my clients to in the middle of a transaction because this broker was able to get the appraisal to go through when their current lender could not. if you would like his hame, please give me a call or drop me an email. I'd be happy to give you his name.
Direct line: 415 380-4630
I realize I am not really answering your question but at this time I do not know of an appeals process. I would talk with your lender and see if they have any suggestions for what you can do. I would also watch the market to see if there are new sales in your area that could help your case and try again. Yes you would probably have a higher rate and would also have to pay another appraiser but if the rate is much better than what you currently have, it could be worth it. Good luck!
Yes, your loan agent should be able to assist you in terms of filing an appeal with the appraisal management company. They usually have a form that is filled out in regards to listing closed sales within the past sixty days along with any pending or active listings. Usually, they want to see 3-5 comparables similar to the subject property. Good luck!