Some homeowners may want to shout "Mayday!" when assessor property valuations arrive this week, but experts say to take a moment to evaluate them properly.

Statewide, except Archuleta County, assessors mailed property valuation notices Friday, something they all do every two years.

Although sophisticated computer models are used to value properties, not everyone will be pleased.

Owners of 5.5 percent of the 2.3 million properties in Colorado filed protests in 2007, a 30 percent jump from 2005.

Even more protests are expected this year.

"There is no ability in the state of Colorado to protest your property taxes," said JoAnn Groff, property tax administrator at the Colorado Division of Property Taxation. "What you have the opportunity to do is protest your value."

Archuleta County's valuations will be mailed a month late, the result of computer problems, officials said.

Below are a few things property owners need to know.

Facts easier to fix than judgment

Valuation notices detail how property owners can file a protest by the June 1 deadline. They can be made by mail or phone, and in some counties via fax, by e-mail or online.

It's easy to challenge factual errors such as a property's square footage, the number of rooms, or a supposedly finished basement that isn't.

More challenging is contesting the value assessors have placed on a home, especially in a volatile real estate market.

One of the most common mistakes people make in disputing valuations is to compare recent sales or appraisals with their property, Groff said.

Assessors review sales over an 18-month period that ended June 30, 2008. Information after that can't be in the appeal.

Finding comps can be trickyAssessments from some of the largest counties are provided online with information used to calculate a property's value. Other assessors will explain what is behind their calculations over the phone.

One of the key tasks in a protest is using good comparable home-sales numbers. Online real estate sites have current sales figures to calculate valuation and aren't very useful.

However, some local real estate agents will provide sales figures from last summer, if only to earn your goodwill.

A new website,, offers Colorado homeowners a free valuation analysis. Mark Linne, an appraiser who helped the state resolve property tax disputes for more than six years, created the site after becoming frustrated helping with a neighbor's appeal.

PropertyTaxSlash charges $49.95 to those who want to lodge a protest with the website's help. At the very least, it offers a second opinion on your assessment.

With protests expected to surge, a weak case based on the wrong comparable sales data can lead to a quick dismissal, Linne said.

"It is a jungle out there," he said. "Most consumers don't have a clue on the rules governing assessments."

Take a deep breath before protesting

Assessors have discretion in throwing out the low and high range of comparable sales, sort of how Olympic judges toss the highest and lowest scores.

In Denver, home values declined 3.2 percent between the June 2005 valuations and June 2007, according to assessor Paul Jacobs. In some neighborhoods, such as Highland and Country Club, valuations have increased by more than 10 percent. And they've fallen by 30 percent in areas such as Montbello and Green Valley Ranch.

Property owners should let their emotions settle and take a second look at their valuation before acting, Jacobs said.

"Think it through," he said. "Is it that out of line with what happened back in June," before the financial meltdown accelerated and caused another downward surge in values?

Seniors should pay close attention to valuations since a break they previously got on a property's first $200,000 in value is set to go away. Their window to protest could be long gone if they wait too long, Linne warned.

This article has been corrected in this online archive. Originally, due to a reporting error, it had an incorrect amount for the break seniors got on their home's value. The break was on a property's first $200,000.