That depends. Defined contribution plans, like 401ks and IRAs, can be easily divided. Defined benefit plans, such as pensions, railroad retirement, IMRF, and TRS are more complicated. Also, it is very common for a retirement plan to have a marital and a non-marital component. For instance, if you have $100K in your 401k when you get divorced, but had $30K in there when you got married, only $70K is probably marital.