Severance agreement arrived, need a second opinion - 2 months and counting

My manager said the package is final, but the letter gives me time to review. It has been weighing on me all week. It includes health coverage for a couple of months. Did anyone negotiate and succeed?

I asked for two more weeks and a neutral reference. They agreed to the reference and added a week.

Keep everything in writing and save the confirmation numbers. It saved me later.