MARIETTA — Property tax assessments are going out today for all 230,000 residential properties in Cobb County, chief appraiser Phil Hogsed said.

About 46 percent of those, 106,370 parcels, will see their assessments lowered, Hogsed said. The assessments are required by a 2010 state law that mandates that counties send every property owner an assessment notice every year, starting last year. Previously, most owners only received such notices when their assessment values changed.

In 2011, 88,500 parcels, or 38 percent, had their assessments lowered, compared to 140,000 in 2010.

The lowered assessments mean fewer tax dollars coming in to county and city governments. The 2012 tax digest is expected to decline by 4 percent. The tax digest is the combined value of all property in Cobb County, and county and city leaders use it to set their budgets and determine how much tax revenue to expect.

The assessments being mailed today will include an estimate of the tax bills that will be sent out in August. It is only an estimate because the county and other local taxing bodies generally set their tax rates, or millage, in the summer. The estimates also don’t include certain exemptions for city residents, such as the Marietta city homestead exemption.

A total of 3,926 homes were foreclosed on last year, Hogsed said,

In Cobb, properties going into foreclosure dropped by 32 percent compared to 2011, while distressed sales were up 37 percent, Hogsed said. Distressed sales accounted for 47 percent of Cobb’s sales activity in 2011.

“A distressed sale occurs when the bank or lending institution sells a property it has taken, or it is sold as a short sale,” he said.

A short sale is when a home is sold for less than is owed on it, and the lender forgives the balance.

Last year, 1,061 new homes were added to the tax books, Hogsed said.

For more information on your assessment notice, log on to www.cobbassessor.org. The tax assessor’s office will answer calls at (770) 528-3100. While taxpayers can find information on filing an appeal on the website, Hogsed said all appeals submitted during the appeal period, which will last 45 days after the date of notice, must be filed in writing — no emails or faxes will be accepted.

Hogsed said that people with questions on their tax estimate should not call the tax assessor’s office.

“Owners may compare the estimate with prior year data on our website,” he said. “It is important to note that if the value is not changed from the prior year, it is likely the tax bill received later this year will remain the same, unless there is a change in tax rates or exemption status. And if the value has been reduced from last year, the tax bill will likely be reduced as well.”

County finance director Jim Pehrson said the county won’t know how much decreased home values will lower tax revenue until it has an idea how many homes were sold in Cobb. That’s because officials don’t know how many people will be able to use the floating homestead exemption, which resets when a primary residence is sold.

Currently, the 2012 tax digest is showing 64,247 floating homestead in the county, for a total value of $1.3 billion. That’s down from 82,280 floating homesteads with a value of $1.3 billion on last year’s digest.

“We’re fairly optimistic right now that we can finish the year without having to go into reserves,” Pehrson said.

Here is the breakdown by location of the residential properties where assessments will be lowered.

* In unincorporated Cobb, 74,416 residential property owners (43 percent) will have their assessments lowered.

* In Marietta, 6,212 homes (42 percent) will have lowered values.

* Kennesaw had 7,726 homes (79 percent) with lowered values.

* In Acworth, 5,192 homes (72 percent) had lowered values.

* Powder Springs saw 3,821 homes (67 percent) with lowered values.

* In Smyrna, 9,138 homes (56 percent) saw values decrease.

* Austell had assessments drop on 1,268 homes (45 percent).