"Retroactive extension" refers to extending something, such as a deadline or a law, to cover a period in the past, rather than just the future. It means the effect of the extension will apply from a previous point in time. Full definition
Also, in December, the President signed a two - year retroactive extension of the Research and Development tax credit through 2011, providing important incentives for companies to invest in America's future. (obamawhitehouse.archives.gov)
Despite a pattern of consistent, and even retroactive extensions, the uncertainty created by the political fight over extending the Production Tax Credit for wind power has caused nearly complete cessation of new wind facilities being brought on line each time the credit wasn't extended well in advance of expiration. (energytrendsinsider.com)
In the past, Congress has enacted retroactive extensions, but such actions can not be relied on for the future. (rismedia.com)