If I have a beer that advances past the first round of the NHC, does the beer submitted to the final round have to be from the same batch? So say I have an IPA that goes through. The bottles from the batch I sent in early March for the first round would have a very different hop character than bottles from the same batch sent in late May. Can we brew another batch using the same recipe for the final round, or do they need to be from the same batch?
No personal experience but many were talking about timing their re-brews last year, so I assume that is the expectation for time sensitive brews
They can be different.
It does not have to be the same batch. You may re-brew and depending on the style, sometimes should re-brew.
It never hurts to re-brew anyway. Then, the day you ship, taste both and send the one you like the best.
Definitely doesn’t have to be the same batch, and I assume if you get an IPA through, you’d really want to rebrew it.
All my entries for NHC are lagers and ciders, so I just bottled up a six pack of each and hold them aside. Nothing worse than getting a entry past first round and realizing you drank the rest of the keg, and now don’t have time to rebrew.
Yeah, you can rebrew the beer, you could even make a tweak to it, but it has to be the same sub-category.
I will probably enter things like lagers and Barleywines, so no rebrew so for me. The lagers will be kept at lagering temps in the interim.
Some styles you should time your rebrew to be at the same stage as when it was judged first round (think Amber or (D)IPA). Other styles like barleywines and such are tougher to rebrew within that narrow window (you’re looking at probably a month to month and a half between results being announced and second round shipping deadlines).
You can totally rebrew and re-tweak any recipe that makes it through to the final round. Have done it many times on both accounts. Still no medal love though… 
The trick is timing the rebrew, as the first round results may not be available until it’s too late to rebrew…
It was interesting tasting the left over final round beers after the banquet last year. Definitely a lot of beers that tasted rushed or old…
June 9th is final round judging date, I believe. I plan my rebrew schedule by that, not by waiting for the 1st round results…