With a more active Atlantic hurricane season expected by forecasters this year, consumers in some areas may notice a rise in insurance premiums. In Massachusetts, state Attorney General Tom Reilly charges those rates may not be justified.

Reilly argues that the insurance industry is using an unexplained model for determining future hurricanes, overcharging for expenses, and inflating its numbers to justify a proposed 12.9 percent statewide rate hike, including a 25 percent increase in the cost of homeowner insurance on Cape Cod.

Reilly filed his final brief with the Division of Insurance, as part of the rate setting case for the FAIR Plan, operated by the Massachusetts Property Insurance Underwriting Association (MPIUA).

In September, the MPIUA filed its request for a 12.9 percent increase for homeowners statewide, a 25 percent increase for Cape Cod, and a 20 percent increase for most of the cities and towns in Plymouth and Bristol counties.

Reilly is recommending no overall rate increase statewide in 2006 - including rate decreases for homeowners in many communities - and a slight increase, 1.2 percent, for Cape Cod homeowners.

"The numbers don't support this request for a rate increase," Reilly said. "The evidence that we've uncovered points to a significantly lower rate than the insurers want. We must do everything we can to keep costs down for homeowners."

The FAIR Plan provides insurance for individuals who cannot obtain property insurance in the voluntary market. Many of the FAIR Plan's customers are middle and low income urban and coastal residents, who cannot find voluntary insurers willing to sell them insurance coverage.

More than 125,000 families in Massachusetts have FAIR Plan insurance.

Reilly argues that insurers are inflating their request by: charging $13 million in backup insurance for the industry; relying on an unexplained hurricane model to hike up coastal rates; ignoring rate caps the Legislature put in place to protect consumers in particularly vulnerable areas like Cape Cod and the Islands; asking for additional funds in case a "demand surge" increases the need for certain supplies after a disaster; and inflating expenses such as debris removal.

Reilly is proposing a 1.2 percent increase for Cape Cod homeowners and a significant decrease in many urban communities, including a 14.2 percent cut for Fall River homeowners. This is the highest among the rate reductions Reilly is recommending for 2006. He is requesting a 7.7 percent decrease for Boston's South End, a 7.3 percent decrease for Charlestown, East Boston, and portions of South Boston, Roxbury and Dorchester, and a 2.1 percent decrease for parts of Roxbury and Dorchester.

Rate reductions for other parts of the state include: a 12 percent decrease for most communities in Bristol County; 10.8 percent decrease for Cambridge and Somerville; 9.8 percent decrease for Quincy homeowners; 9.3 percent decrease for Worcester homeowners; 6.8 percent decrease for homeowners in Chicopee and Holyoke and several towns in Middlesex County, including ; 4.9 percent decrease for Lawrence homeowners; and 4.1 percent decrease for Lynn homeowners.