But the court determined that the tax's application to rental income amounted to a tax on real property, violating the Constitution's "direct tax" clause.

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They filed non-resident Montana tax returns reporting the rental income on their two properties.

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That means 81% of the expenses listed above can be written off against the rental income on the owner's Schedule E, according to Abe Schneier, a tax specialist at the American Institute of CPAs.

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