There is no such thing as a federal "inheritance" tax. Only a US EState tax.
She will not owe the IRS any estate tax. Depending on the size of father's estate, not yet disclosed, and depending on year of death, estate taxes may be due or have adlready beed paid. That is the responsiblility of the executor as a general rule.
Moving on to possible state estate or inheritance taxes.
Would she owe any state taxes?
Answer: Maybe! It depends on state law where father was domiciled
and also state law where the real property is located.
If your father in law was a GA resident and the property was located in GA, you/she are home free. GA has neither an inheritance nor an estate tax:
https://etax.dor.ga.gov/inctax/webfaq/faq-est.aspx#1
Q. Does Georgia have an estate tax? Does Georgia have an inheritance tax? How does Georgia's estate tax work? What is the tax rate? How do I compute the tax? Can you send me a Georgia estate tax return or information?
A. Georgia has an estate tax for estates of decedents with a date of death before January 1, 2005 which is based on federal estate tax law. Georgia has no inheritance tax, but some people refer to estate tax as inheritance tax. The tax is paid by the estate before any assets are distributed to heirs. It is not paid by the person inheriting the assets. Georgia 's estate tax is based on the amount allowable as a credit for state death taxes on the federal estate tax return (Form 706). Use the tax table in the federal instructions to compute the credit. The amount paid to Georgia is a direct credit against the federal estate tax. Click here to go to the IRS’ website.
The Economic Growth and Tax Relief Reconciliation Act (“EGTRRA”) of 2001 (H.R. 1836) modified the estate tax.
For individuals dying in 2002, the state death tax credit is reduced by 25% from the pre-2001 EGTRRA amount; for individuals dying in 2003, the credit is reduced by 50% from the pre-2001 EGTRRA amount; for individuals dying in 2004, the credit is reduced by 75% from the pre-2001 EGTRRA amount; and for individuals dying in 2005 and after the state death tax credit was repealed and replaced with a deduction.
Therefore, for estates of decedents with a date of death after December 31, 2004, Georgia estate tax does not apply to any estate with a date of death that occurred in a year for which the Internal Revenue Code does not allow a credit for state death taxes.
Georgia does not have an estate tax form. You must file a copy of the federal return with payment for the Georgia tax. The due date is the same as the federal due date, 9 months after the date of death. If no Federal estate tax return is required to be filed, no Georgia filing is required. Further information is available from the Georgia Department of Revenue’s Estate Tax Section.
Q. Where do I send the return and anything else related to Georgia estate tax?
A. GeorgiaDepartment of Revenue
Processing Center
P O Box 740320
Atlanta, GA30374-0320
Final point:
Is a Capital Gain tax due on sale by wife.
Answer: It depends!
Most states follow the normal federal rules of "basis". For property inherited, that becomes the fair market value at date of death of decedent. There is a possible exception for 2010 deaths. If his estate was more than 1.3 million, then his exexcutor has the option to select which assests to "step-up" to fair market value. This was the trade off for the 1 year expiration of the federal estate tax. However..........
Congress in Dec brought back the estate tax option for 2010 deaths and gave the estate the option of either skipping the estate tax and keeping the limited 1.3 million step up OR using the new rules which tax estates greater than 5 million and
also restores the step up rules to all assets, regardless of value.
First thing to clarify. Does GA use federal basis rules?
If so, determine FMV at his date of death.
Next and most important thing thing to determine. Has the property appreciated in value since he died? Has it depreciated in value since he died
Comparing date of death value to a proposed selling price (less costs to sell) will determing whether you have a capital gain or loss.
The holding period for inherited property is deemed to be long term in all cases. Doesn't matter if he bought the property at 9:00 am and died at 3:00 pm on the same day.
Hope this info is useful to you.