Ok ... first any RMD required of the decedent must be taken first ... then the balance is rolled to the spouse's IRA and is then treated as any other IRA for that person. An RMD is only required if that person has that requirement.
Inherited from spouse. If a traditional IRA is inherited from a spouse, the surviving spouse generally has the following three choices:
Treat it as his or her own IRA by designating himself or herself as the account owner.
Treat it as his or her own by rolling it over into a traditional IRA, or to the extent it is taxable, into a:
a. Qualified employer plan,
b. Qualified employee annuity plan (section 403(a) plan),
c. Tax-sheltered annuity plan (section 403(b) plan),
d. Deferred compensation plan of a state or local government (section 457(b) plan), or
Treat himself or herself as the beneficiary rather than treating the IRA as his or her own.
If a surviving spouse receives a distribution from his or her deceased spouse's IRA, it can be rolled over into an IRA of the surviving spouse within the 60-day time limit, as long as the distribution is not a required distribution, even if the surviving spouse is not the sole beneficiary of his or her deceased spouse's IRA.
https://www.irs.gov/retirement-plans/plan-participant-employee/retirement-topics-beneficiary
