Mississippi Power Company says customers won't have to pay more to cover the plant's cost, which has risen from $2.88 billion to about $3.42 billion.
Ed Day, president and CEO of Mississippi Power, said in a news release Tuesday that workers are making progress on the facility.
However, Day says Mississippi Power has had additional expenses including labor costs, piping and other material costs, engineering and support costs and productivity decreases.
Day says Mississippi Power will keep its promise made in a settlement agreement with the Mississippi Public Service Commission to limit the total rate base for the plant to $2.4 billion.
The PSC approved a 15 percent rate increase in March, to be followed by a 3 percent rate increase in 2014.