Go to your CPA who does taxes. He or she will have an electronic tax library such as BNA. There is a portfolio written by tax attorneys on "Reductions in Force". Get that. Download that into Microsoft Word and have him or her send it to you.

There is more than just 15 months. There's accured personal time off that can be big. I mean a big tax bite that may take you into a higher tax bracket. That's why a lump sum may not be a good "after tax" decision.