When all you have is a hammer…

I received my 2017 property valuation notice from Boulder County, and they listed the value of my house way above what it’s worth. According to them, it increased in value by over $80,000 last year! It’ll mean another $700 in property taxes. Not cool.

So I went to the Boulder County assessor’s site to figure out how to protest this valuation, and they provide some search tools so you can find comparable properties. They use “time-adjusted” sale prices, all calculated for June 2016 (the time of the valuation), so it’s a relatively simple matter of finding homes like mine, seeing their sale prices, and finding an average.

Of course, with tens of thousands of homes in Longmont alone, that “relatively simple” matter gets complicated quickly. Looking at a map isn’t a good way to identify homes of roughly the same square footage, or with a similar basement or yard or year of construction or whatever. Luckily the county provides a downloadable Excel spreadsheet that lists properties which sold in the past two years (which is the time period for the valuation). I downloaded it, and was a little dismayed to find that it contained 5,900 property records. Hmm.

Sorting by square footage was a first step, but not useful because I’d find houses the same size as mine, but 50 years older… or without a garage… or in a ranch style. After a few futile attempts to sort the spreadsheet in a way that would show me comparable homes, it occurred to me what to do. I’m a database programmer, right? So I wrote a little PHP script to load the spreadsheet data into a database that I’d quickly created, and pulled all of those values into the appropriate fields.

Then it was a relatively simple (I keep using that phrase…) matter of writing some SQL queries to find homes that matched my criteria, and calculate the average of their sale prices. I could look for homes with floor space within 100 square feet of mine, or built within a few years of mine, and so forth. After a few queries I narrowed it down enough to identify some houses that were more similar to mine than the ones the county had selected. I went back to their web site, filled out the protest form, and submitted my calculations. In three months they’ll respond whether they accept my proposed valuation, and hopefully my tax bill will be $700 lower.

I’m not sure what other people do in a situation like this, but if you’re a database guy…