A Midwestern insurer says it will be reducing its workforce by about 4% and recording investment loss charges that will cut fourth-quarter 2008 net income about $12 million.

The insurer, FBL Financial Group Inc., West Des Moines, Iowa, says it also will postpone its earnings release date to Feb. 19, from Feb. 5, so that it can include unrealized investment loss figures that will match the figures in its official Form 10-K annual statement filing.

The charges will be due partly to the cost of unlocking deferred policy acquisition costs, FBL says.

FBL is taking DAC-related charges because a recent drop in Treasury rates has led to an increase in surrender rates for indexed annuities and multi-year guaranteed annuities, the company says.

FBL will recover some of the unlocked DAC costs in later years, based on the future profits of the underlying business, but the increased surrender rates also could affect the profitability of the underlying business, the company says.

In an effort to control costs, FBL is freezing executive salaries, eliminating empty positions and laying off 76 employees.

In the past, the company has said that it has had about 1,800 employees.

Most of the cuts will affect employees in the home office, FBL says.

FBL is taking $1.2 million in charges in connection with the workforce reduction.