There will not be any federal estate tax.
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In addition to Attorney Reed's answer, there would be no inheritance tax in Iowa, if you were the surviving spouse. Because it appears that is not the case, you would want to visit with an attorney or CPA to discuss this, further. Your tax could be as much as 10-20%, unless you can show that you were married under common law. Iowa appears to be one of the states that recognizes common law marriage, under certain circumstances. The three elements of a common-law marriage are: (1) the present intent and agreement to be married; (2) continuous cohabitation; and (3) public declaration that the parties are husband and wife. Martin, 681 N.W.2d at 617. The public declaration or holding out to the public is a crucial part of the equation.
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If you aren't the spouse of the homeowner, then you will pay inheritance tax. Stated most simply, the tax for an unrelated person such as yourself is 10% on the first $50,000, 12% on the next $50,000, and 15% on any value above that. The calculation of the taxable estate is a bit more complicated. You should contact a probate attorney to discuss the estate and perhaps help you or the family probate it.
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