Marleen Gamble had already taken out a reverse mortgage on her townhouse in 2018 to keep up with the steady increase in expenses eating into the Social Security checks that are her only source of income.

Then this year, Ms. Gamble, a retired X-ray technician, faced a 20 percent spike in her property tax bill. With no other way to pay it, she began to empty her home of 34 years in the Denver suburb of Littleton, one memento at a time. Her dining room set, sold. Her jewelry, now someone else’s.

“Every knickknack I have, everything I don’t use, I’m selling,” said Ms. Gamble, 84, who has asked officials in neighboring Douglas County about applying for subsidized housing. “What I owe now is $962.62. I think I need to use two credit cards to do it. And I’m going to have to pay interest on those.”

Skyrocketing property taxes have become a sudden new source of alarm for many people these days in Colorado, and across the newly booming states of the Rocky Mountain West.

As home values have soared, fueled by a pandemic real estate boom that turned large swaths of the Mountain time zone into magnets for hybrid work and recreation, so, too, have property taxes. And while the rates remain low compared with places like New Jersey, Vermont and Texas, the sticker shock in Mountain States has been discombobulating, especially for low-income families or people who own second homes.