State Farm Fire and Casualty Co., which insures around 30 percent of the homes in Louisiana, plans to raise its homeowners’ rates an average of 8.5 percent statewide, according to a filing with the Louisiana Department of Insurance.

The proposed rates will affect 301,048 policyholders and generate $32.7 million, according to the filing.

State Farm’s filing contains a number of proposed changes, including:

• Using credit ratings and the length of time a homeowner has insured his vehicle with State Farm to calculate the rates for all policyholders.

• Introducing an optional 4 percent hurricane deductible.

• Splitting out the portion of the premium that covers hurricane exposure from the basic homeowner’s premium.

According to State Farm, the split premium will allow it to more accurately price both types of risk.

Spokeswoman Molly Quirk said rates will vary depending on the amount of hurricane risk a customer’s home faces.

“We can’t yet share how much different the rates will be in different areas. Those specifics are proprietary and confidential until the DOI (Department of Insurance) acts on the filing,” Quirk said.

While the cost for homeowners’ insurance varies, in gener-

al the coverage is more expensive in the coastal areas of the state.

Insurance Commissioner Jim Donelon said a half-dozen other firms, including Allstate, already use the split approach in calculating premiums.

The approach will allow State Farm to make more detailed assessments of the risk from hurricanes and other potential losses down to the parish level, Donelon said.

One change will be that homes in a parish that lies south of the Gulf Intracoastal Waterway will be treated as a higher risk than those north of the waterway, he said.

The split approach can result in higher rates for people with higher hurricane exposure, but those increases are offset in the state by lower rates for people with lower hurricane exposure, Donelon said.

If approved, the new rates will become effective Aug. 15 for renewals of existing policies and on Oct. 1 for new policies.

In order for the filing to be approved, the department’s analysis must find that State Farm’s request to increase its rates is statistically justified, Donelon said. There are a variety of factors that go into the analysis.

“I’ve rejected other rate increases in the past, and this one is under review,” Donelon said.

In March, Donelon rejected State Farm’s request to increase homeowners’ rates by an average of 14.3 percent.

At the time, Donelon said the company had built in too large of a profit in its rates. Donelon also questioned the catastrophe models State Farm used in calculating the rates.

In 2010, State Farm asked to increase rates by 19.1 percent, but Donelon rejected that request, describing it as unreasonable. State Farm later received approval to raise its homeowners’ rates by 9.9 percent.

In the current filing, State Farm is offering customers the choice of a 4 percent hurricane deductible.

Quirk said most of State Farm’s homeowners’ policies carry a 2 percent hurricane deductible.

However, the company also offers optional 5 percent, 10 percent and 15 percent hurricane deductibles in some parts of the state, she said. The 4 percent deductible provides customers with another option.

State Farm does not disclose the percentage of customers who opt for the larger deductibles, Quirk said. The information is proprietary, and something State Farm’s competitors would like to know for business purposes.