Skyrocketing home values are not all good news for homeowners. In King County, some are being put on notice now that a big bill could be coming soon.

Tim Sandner says he bought his home in Rainier Valley six years ago for $270,000. Today, he says it is valued around $475,000.

"I think it's good,” said Sandner. “I mean property values going up means your area is kind of on the rise."

At the Office of the King County Assessor, they agree Rainier Valley is on the rise. Home values are spiking 19.3% on average in the area. In White Center, home values have climbed 18.6%, in Bellevue 19%, and SeaTac more than 21%.

"It could mean several hundred more dollars a year that you are going to be paying in property taxes," said assessor John Wilson.

Wilson says two factors are driving up home property taxes. One, values continue to climb as people clamor to buy in a competitive housing market. And two, the ballot measures voters approved are part of it.

"This is the first time Sound Transit has been part of the property tax equation for most King County taxpayers. In Seattle, you've had several levies that were passed, including one for affordable housing," said Wilson.

The Office of the King County Assessor is sending out notices to more than 700,000 property owners. The notices will continue to arrive through September. If you feel the notice you receive is not correct, you have 60 days from when you receive it to appeal.