If your value is really out of wack compared to the rest of the town, the Assessor will adjust the value. You just need to come in with comparable sales etc. However, if your just off 10% or so because of the decline in the overall RE market, they won't adjust your valuation. This is because they would have to reduce everyone's valuation... And then they'd just crank up the mill rate and you'd end up paying they same tax anyway. The town needs to collect a certain amount of $s.
You can go to your Town Office and ask the Tax Assessor for a Tax Abatement form. You should seek the assistance of a qualified Realtor in your area to provide you with Comparable Sales in your town that you can submit with your Abatement Request. If you need a referral to a Realtor in Kennebunk, let me know. I would be more than happy to help you! Give me a call at (207) 975-9330!
Blessings!! Steve Dyer