A mother inherits the IRA of her deceased son, who was age 50 or so (the mother is in her 70's). Can the mother treat this as an inherited IRA and spread the distributions out? The broker says that since it's going from son to mother, the entire distribution is taxable in 2004, the year the brokerage account was "liquidated". The mother would like to put the money back in the IRA and spread the distributions, if possible.

Any replies would be appreciated.

It’s too late. Once the assets are distributed to a non-spouse beneficiary, they cannot be returned to an IRA- including an inherited IRA. Had the mother left the assets in the IRA or transferred (non-reportable trustee-to-trustee transfer) it to an inherited IRA, then the assets could have been distributed over her life expectancy.

I was confused about tax-free transfers for a non-spouse beneficiary until I stumbled upon this is Publication 590: "However, you can make a trustee-to-trustee transfer as long as the IRA into which amounts are being moved is set up and maintained in the name of the deceased IRA owner for the benefit of you as beneficiary."

Right. And the TIN of the beneficiary must be used, so that all tax reporting for transactions that occur after the death of the IRA owner is reported under the TIN of the beneficiary