A 5.5 percent increase in real estate tax assessments pushed Orange County’s total taxable property values above the half-trillion-dollar mark for the first time, the Orange County Assessor’s Office reported Wednesday.

The county’s 2016-17 tax roll totaled $526 billion, with real estate accounting for nearly $506 billion of that.

The assessments are used to gauge how much property tax owners will pay next December and April, when the first and second installments come due.

The increase of $27.1 billion in total assessments means the bulk of local property owners will have a tax hike this year.

It also translates into increased revenue in all Orange County cities to pay for roads, police, fire, pensions, parks and dog catchers. The county, public schools, water districts, libraries and other special tax districts will see increased revenue, too.

Still, the county’s 900,000-plus owners of homes, apartments, office towers, warehouses, factories and other buildings will get a slight – make that tiny – break this year. The biggest tax hike allowed for most owners under Prop. 13 will be just over 1.5 percent, instead of the maximum allowable increase of 2 percent.

In other words, the owner of a home assessed at last year’s median price of $582,000 will see his or her tax bill increase by about $89 instead of the maximum allowable $116, a $27 savings.

The savings might be more significant for the owner of a $50 million office building: His or her tax bill will be about $2,400 cheaper this year.

The reason is inflation was a tad lower last October, on which the tax-hike rate is based. Tax hikes have been below the maximum 2 percent in just 10 of the 42 years since Prop. 13 took effect, assessor’s figures show. Taxes have gone up in 41 of those years.

Some property owners who had tax cuts in past years due to falling real estate values may see even higher tax hikes this year – some as high as 30 percent or more – due to the market recovery.

Under Prop. 13, county assessors can boost your taxable assessment back to where it would have been had property values not dropped.

Owners of Orange County’s 25,000 boats, 809 aircraft and 95,549 businesses also will face tax hikes on taxable “personal” property they own. The countywide assessment for such “unsecured” property is up $297 million to $15.8 billion.

Irvine remains Orange County’s most valuable city, with a tax roll of $65.9 billion, the assessor’s office said. Newport Beach ranked second with a $50.5 billion tax roll, followed by Anaheim with a tax roll of $41.4 billion.

Orange County’s smallest city has the smallest tax roll. Villa Park, population 5,948, has a total tax roll of $1.7 billion.

Lake Forest, home to the Baker Ranch new home development, had the biggest percentage gain in its tax roll this year: Up 8.1 percent. Seal Beach’s 1 percent increase was the county’s smallest gain.

Tax assessments are pegged to property values on Jan. 1.

Prop. 13 gives real estate owners a huge tax break.

Under the voter-backed 1978 initiative, a home or building’s assessment is based on its fair market value when a new owner buys it.

In subsequent years, tax hikes are capped for that owner by the rate of inflation, up to a maximum of 2 percent a year. The 2 percent maximum remains in effect so long as the owner retains title to that property, even when property values are soaring by 20 percent or 30 percent a year.

Residents who disagree with the assessor’s property appraisals normally have up to Sept. 15 to file an appeal through the Orange County Clerk of the Board’s office. But Orange County Assessor Claude Parrish extended the appeals deadline through Nov. 30 for a second straight year.

Owners with questions about how their assessment was reached can call the assessor’s office at 714-834-2727.

Contact the writer: 714-796-7734 or jcollins@ocregister.com