Portions of a pension or retirement account, which have accumulated (either by contributions, or passive increase in the value of invested assets) during a marriage, are considered to be marital property. These may be divided by a judge as part of a divorce or by the parties as part of a divorce agreement.
The law permits all or portions of plans such as IRAs and 401ks to be transferred as part of a divorce outcome without incurring tax or penalty for withdrawal. The law also permits fixed retirement plans such as Colorado public employees retirement association benefits [PERA] to be divided as those benefits are paid out over the lifetime of retirement.