If Congress does act to retroactively reinstate the donation rule, the gift will be excluded from income just as under the pre-2012 rule.

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The act of retroactively canceling insurance is called rescission.

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But in Hamdan, the high court held that the 2005 act did not apply retroactively, so that habeas proceedings already under way could continue.

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When the Supreme Court decided it last week, the justices said the Detainee Treatment Act did not apply to Hamdan retroactively.

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The Act both extends favorable tax treatment for such stock acquired in 2013 and retroactively applies it to such stock acquired in 2012.

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