THE TIME FOR procrastination is over. If you own property in Philadelphia, the deadline to file a first-level appeal of your new property-tax assessment is Monday.

If you think your property is worth less than your city assessment, you should submit as much hard evidence as possible. You can also appeal if you think your assessment is out of whack with similar properties in your neighborhood, or if the city described your property incorrectly.

But be careful. Philadelphia's chief assessment officer, Richie McKeithen, said an appeal won't always lower your assessment.

"I'm against people filing appeals for the purpose of filing without doing any due diligence," he said. "You can wind up divulging information that we might not necessarily have, and information that could wind up resulting in an increase in your value."

There is one exception to the Monday deadline: You can file a first-level appeal up to 30 days after receiving your new assessment, if that date comes later.

You can find a simple application for an appeal on the Office of Property Assessment's website ( If you miss Monday's deadline, you can make a formal appeal to the Board of Revision of Taxes by Oct. 7.