Retirement accounts are not typically transferable between anyone, even spouses, without tax consequences. In order to transfer funds held in a retirement account the owner must first remove them from the retirement account, which, if allowed by the rules of the plan, will result in taxable income and, prior to retirement age, tax penalties.
However, in the event of a divorce the IRS allows for a one-time transfer by Qualified Domestic Relations Order (also known as a "QDRO") to avoid these taxes and penalties. A transfer of retirement account between former spouses pursuant to a QDRO results in a new retirement account held in the name of the other spouse (or "alternate payee") in the amounts and per the terms specified in the QDRO. The retirement income paid from said account will be taxable income upon receipt just as it would have been to the original owner, but the transfer between spouses is not taxed at the time of the transfer.