Depends on how often you see them. If it's your wife - it is definitely too late.

12:00:01

I think right up to the end of January is fine for someone you haven't seen yet in 07. But here in New Zealand we've just ticked over to the 1st of Feb and that's where I draw the line.

I think that within a couple weeks onto January.

No more.

But I like Justin's idea though.

I vote for 7-10 days after and no later. I hate saying it at all. Still, some people will say it the first time they see you in January of said new year. I got that at a party on the 20th and it just felt wrong. But she's really annoying anyway.

I think February 20th is good.
That way you get the Chinese New Year in there as well.

There is no cutoff date. If they raise an eyebrow, claim that today is the New Year in the Malthusian calendar (or your own favorite bogus Jon Hodgman-esque term ... Kottkeian).

Feel free to wish them Gung hei fat choi (2/18, this year). You can be early!

I have often wondered about this. I've noticed folks look at you askew any time after the first week after the new year when you wish them a happy new year. they say 'oh. right. er, happy new year'.

You obviously have to consult Seinfeld for such a dilemma.

I overheard someone saying it today and it was the first time it's sounded weird to me. This post showing up today is too big a coincidence to ignore, so clearly the answer is: yesterday, January 30th was the last day it was okay to say "Happy New Year."

By the first Friday of the new year. After that, you just sound like a goof. But then again, I still see people with their Christmas trees set up.

September 23rd

Never if you're clever.

http://fullchordpress.com/about.html

I tend to wish people I haven't see all year a happy new year for the first few weeks of January - no longer than that.

Let me be the last to wish you a 'Happy New Year'.

Eh -- my family just celebrated Xmas the weekend before last, so late is better than never, I guess.

The next Federal holiday following New Years. In this case, January 15th... Martin Luther king Jr. Day.

I'd draw the line at January 15.

The last day to say Happy New Year is the end of the first work-week of January. If you haven't had a chance to see your coworkers and wish them an obligatory prosperous new one, you honestly don't really care if they have a good year or not. What's the point, then?

So the end of the first work week in January. Unless you celebrate a different new year, but they typically have their own name for you to wish someone. For example, you would be very late wishing someone a happy Rosh Hashanah

I just sent them ! :)
Well, actually, yesterday, the 31st. Apparently here in France that's the limit.

Happy New Year!