The company has launched a consultation placing a question mark over 100 positions.
The results of the review are due in mid April and could take the total number of redundancies to 150 following last year's round of losses.
A Constellation spokesman said: "We are now in the process of consultation.
"All of this is still as a direct consequence of duty and that's not predicting what it will be after the Budget. This is about managing last year's increases."