Here's a salary negotiation script to negotiate for a severance package.
Dear Mr. Recruiter,
Thank you for offering me the Lead Developer position. I’m excited about the job and I’m confident that I can bring a lot of value to Company Z. I’m glad that we could work out the terms of the salary and the compensation package.
Before I can accept, I have one last aspect I would like to talk about. I am concerned about the lack of a severance package. I am a very thorough person, so I would like to solidify the terms of a severance package before I accept. I do not anticipate creating a reason to get fired, but I would like to know what would happen if a layoff did occur. In particular, six months wages and continued health and dental insurance coverage for nine months seems like a typical and appropriate severance package. Of course, discussing the severance package will not cost the company any money up front, and if I am never laid off, the company will not pay any money at all.
Once we solidify the details of the severance, I’ll be ready to accept the job offer.
Thank you for your time and consideration,