If the attorney needs input from the accountant as to what's included in the estate, you should reconsider your choice of attorney. Most estate tax returns are done by law firms, and law firms with trusts and estates practices do them on a regular basis.
The Federal estate tax exempt amount is $5,120,000. The Maryland estate tax exempt amount is $1 million. There is a marital deduction for assets passing to the spouse. However, assets passing to the spouse will be included in the spouse's estate. Most married persons create a credit shelter trust in their Will, so that the exempt amount will be available if the spouse ever needs it, but will not be included in the spouse's estate.
In a state like Maryland where the Federal exempt amount is higher than the state exempt amount, you have to decide whether to shelter the entire Federal exempt amount (or as much of it as you can), at the cost of paying some state estate tax, or whether to only shelter the state exempt amount. There are some variations among the states that have such estate taxes. However, a discussion of that is beyond the scope of this forum.
The executors can elect portability. If they elect portability, the unused exempt amount will be added to the spouse's exempt amount. In this case, if $1 million passes to a credit shelter trust (this seemed likely from the facts presented, but it wasn't clear), the remaining $4,120,000 exempt amount (assuming no other assets passed to anyone other than the spouse) will be added to the spouse's exempt amount. Portabiity is scheduled to expire at the end of this year (in which case the ported exempt amount will vanish). However, the Administration has proposed making it permanent, and no one has expressed any opposition to doing so. Note that portability doesn't apply for state estate tax purposes, nor for generation-skipping transfer tax purposes.
The above illustrates how planning for smaller (under twice the Federal exempt amount) estates can sometimes be more difficult than planning for larger estates.
In general, in the case of assets owned jointly by a husband and wife, one-half is included in the estate of the first spouse to die for estate tax purposes (even though it's not a probate asset), and since it passes to the spouse, it qualifies for the marital deduction. There's also a basis step-up for that one-half interest. However, in some cases, if the property was acquired before 1977, the entire value of the property may be included in the estate for estate tax purposes (in which case the entire value will get a basis step-up and will qualify for the marital deduction).
The retirement benefits are also included in the estate for estate tax purposes. However, if they pass to the spouse, they'll qualify for the marital deduction. The spouse can also roll them over into her own IRA, and (if appropriate) convert to a Roth.
In response to mathwizard: an asset payable to a beneficiary is included in the estate for estate tax purposes, even though it's not a probate asset. Most lawyers handle estates on a time basis rather than on a percentage basis. However, on the infrequent occasion where (at the client's request) we take one on a percentage basis, we do it as a percentage of the gross estate for estate tax purposes rather than a percentage of the probate assets. There's often more work dealing with retirement benefits (setting up inherited IRAs, advising as to required distributions, advising as to the income tax deduction for the estate tax) than on other assets. The fees on most estates would be far less than 6%, but they're likely to be a larger percentage on a smaller estate than on a larger estate, though sometimes a smaller estate can be complicated and a larger estate uncomplicated. We might not take a $600,000 estate unless we had some other relationship with the client or the referral source.
Naming a beneficiary for assets other than retirement benefits (where you need to name a beneficiary to get the stretchout) and life insurance (to protect the proceeds from creditors) is usually not a good idea, though for $100,000 it's not a big deal. It's not a major concern for small amounts, but we've seen cases where financial advisors were the driving force in having beneficiaries named for large accounts, and it wreaked havoc on the estate plan.