The Senate Regulated Industries and Utilities Committee passed the bill 8-2 on Wednesday. It now goes to the full Senate.
Georgia Power officials argue that recouping the interest costs means ratepayers will pay less in the long run. They estimate it will shave $300 million off the $16 billion expansion.
The company wants to expand its nuclear facility at Plant Vogtle near Augusta years before the construction is completed.
Georgia Power customers would see their bills rise by an average of $1.30 a month beginning in 2011 under the bill.