I could probably fax(or snail mail)you a copy of PLR 9630034 if you don't have access to IRS private letter rulings. Most attorneys or CPAs will have a service that gives you copies of these rulings. The system where I have them isn't e-mailable (at least not with my computer talents).

In that ruling, the beneficiary was the wife, the contingent beneficiary was the family trust. Some advisors recommend being more specific and naming the Bypass Trust to be created from the family trust. Your beneficary designations should list the trust as the contingent beneficiary.

When the owner passed away, the IRA was partially rolled over (and retitled in name of surviving spouse), the portion disclaimed would have been listed in the decedent's name like this:

John Jones, IRA, Jones Bypass Trust, beneficiary
The EIN of the trust (not the decedent's SSN) would be associated with the account.

During the lifetime of the surviving spouse, each year's RMD (based on the spouse's life expectancy the year after the death) is transferred from the IRA to the Bypass Trust. The distribution will be taxed to the trust if it isn't distriuted (since you're trying to save estate taxes you may incur income taxes to do so). The original life expectancy is reduced by 1 each subsequent year, the spouse's death would not accelerate the RMDs unless the Bypass Trust had a provision to do so.

No further contingent beneficiaries can be named that will extend the payout period of the IRA. The spouse's life expectancy will be the longest period you can use.

If you want a "stretch" then the spouse must do a rollover and name new beneficiaries; those beneficiaries can use their own life expectancies. It's a difficult decision to decide if you want to grow the IRA by using the stretch out available or save estate taxes at the spouse's death by using the Bypass Trust.

I hope this clarified your questions.