They were retroactive - but you can't retroactively lower GDP growth. They can only have an influence in quarters going forward. The argument of a growing economy producing more revenue is the same we see when analyzing the effect of a tax cut. The economy was growing when the 2003 cuts took effect, as well, mind you...
But the result after the tax increase (and it should be noted that it was very clear early in the year that clinton was going to reneg on his campaign promise of middle-class tax relief and seek a major tax increase -- businesses and investors started planning accordingly even before the tax hike became law) growth started SLOWING almost immediately. After the Bush tax cuts, the economy started growing at a faster rate. And still reeling from 9/11 and the war on terror, the economy picked up steam following the second round of Bush tax cuts. Oh, and by the way, what precipitated that brief recession during the term of GHW Bush's presidency? Oh yeah, it was that compromise with the democrats tax increase that caused him to be a one-term president.
Clinton's tax hike didn't pass until August 1993, but we knew it was coming.
February 15, 1993 : Less than one month after Inauguration, Clinton backtracked from his campaign promise to lower taxes for the middle class. From the oval office Clinton said "I had hoped to invest in your future by creating jobs, expanding education, reforming health care and reducing the debt without asking more of you ... but I can't."
I don't suppose you think this knowledge could have reduced growth before August 1993?
We went from +4.2, +3.9, +4.0, +4.5 in 1992 to +0.5, +2.0, +2.1, +5.5 in 1993. I guess the drop from +4.5 to +0.5 happens all the time at that point in a recovery? Nothing to do with anticipated hikes? And you know why the 4Q93 growth was so high, don't you?