The parties agree that Husband shall have a 50% interest in the share of Wife's pension. "
Marital share " shall be define and calculated as follows: Marital share = Mos. Of Service During Marriage at Date Of Separation. Total Months of Service at Retirement
Divorce / Separation Lawyer
It appears from your posting that your agreement defines the marital share.
To make the math easy, let's assume 21 years of total service toward pension/retirement. Seven years were during the marriage. Fourteen years were outside the marriage.
7 marital years divided by 21 total years is one-third. Husband gets half of the third or one-sixth.
You could also multiply the years by 12 to get months as provided in the agreement, but the result is still one-third.
Whatever pension check the wife is entitled to, husband gets one-sixth. If wife's check is $1,000, then husband gets $167.