ABV Question

The ABV of a brew is easily determined from two simple readings ,the Original Gravity and the Final Gravity. These only require hydrometer readings which take only minutes. The ABV can be easily calculated from these with acceptable accuracy.
In the UK beer tax is levied on ABV and the tax authorities accept such figures
No doubt random spot checks are carried out but breweries are self assessed.

 

It is the TTB, they do spot checks. Larger breweries know what the ABV is as they have precision lab equipment.

 

Of course with live beers the delivered ABV will be a bit higher than the measured value because of the primings and secondary fermentation.

 

Does the FDA test every food product on the market to make sure the Nutrition Facts table is accurate? Suffice it to say, FDA and TTB might do spot checks here and there, mainly if there's a complaint, but companies know that there would be lawsuits and other massive legal problems if they're caught lying. On the other hand, as alcohol content can change in the bottle, there is some leniency given.

https://www.law.cornell.edu/cfr/text/27/19.600

Some other good info here:
http://www.beeradvocate.com/community/threads/how-accurate-are-craft-beer-abv-percentages.149261/

 

It is regulated, and it is checked. But probably nowhere near as much as regularly, nor most likely until they have a reason to. The brewery does have some fudge room over and under the established abv they have listed on the label.
Barrel aged beers are probably the one style that can be quite a bit higher than what the abv lists. Especially when the lead time needed to get the label and what it is going into back in house can be 6 to 8 mos. You might know what the original abv is. But, it could climb as much as 3 or 4%. But not necessarily.

 

I know at least one brewery in a state outside of WA that brewed a beer that eclipsed their state's abv cap. They didn't do it intentionally. They ended up lying about the abv and released it anyway. This was several years ago and there were never any repercussions.

 

To expand on @hopfenunmaltz' s post, from the TTB:

TTB's Sampling Results for 2015 notes that of the mere 158 malt beverages checked:

So, what's that - an average of almost a quarter of the ABV's were wrong - 18% higher and 6% lower. But the variances, though outside the allowed tolerance, were relatively small (although that would depend on the beer - a 4% abv "session" beer vs at 12% barleywine).

As noted on the same page, consumers can even file an official complaint:

 

I'm surprised that the average "underproof" products were almost 1% on the low side. I would think that if you know O. G. and A. A. of the yeast you could predict F. G. and get a little closer than that.

 

I would imagine that is more a factor of a brewery not printing a new label every time the ABV of a batch of beer comes out slightly above or below the TTB tolerance level.

"Tens of thousands of batches of beers released, 158 randomly checked by the TTB.
What's the chance that we get caught?" ​

Bigger brewers could blend batches to get the abv within the correct range, especially for their regularly brewed beers, and high gravity brewers would adjust the quantity of water added. Not sure what the penalties are for incorrect ABV labels. (Unlike wine and spirits, the Federal excise tax rate is not based on the alcohol content.)

 

I mentioned earlier that UK breweries operate a self assessment scheme for declaring ABV. This figure is the basis for taxation purposes but there is no temptation to falsify as it isn't the brewer who pays the tax but the final customer.
Her Majesty's Revenue and Customs no doubt do spot checks and certainly compare the declared output with invoices for ingredients.All the brewers I know (which is a lot) simply do the measurements and tell HMRC. It's no big deal for them , just a touch more paperwork. As one brewer once told me , "it simply isn't worth the hassle to try to fool them"