They assess annually as of 1/1 and its supposed to represent 100% market value. Thus the assessment can increase to or above the sales price upon sale. Also it will increase if they think that is the market value - there is no phase in like in DC. They try to inspect every few years but I don't think they typically try to enter your house. They use a mass appraisal model based on sales in your neighborhood during the prior year (so 2013 sales for the 2014 assessment). You can see the sales they use when you look at the assessment page on-line.

No idea. I think it's based off of recent sales in your neighborhood. They've never sent anyone to my house to inspect it like an appraiser would when you buy/sell. They definitely raise the appraisal numbers and taxes yearly! Last year we had a $700 increase just for the privilege of living here...

in the butt

Annually? How?