Since the enactment of the CIDER Act, the cider tax rate ($0.17/gal) applies to products that are under 8.5% ABV, under 0.64 gram of carbon dioxide per 100 milliliters and contain no other fruit than apples or pears.
As of January 1, 2019, the TTB is requiring all cider (not just cider >7% ABV) that qualifies for the cider tax rate to be labeled with this statement: Tax class 5041(b)(6). The requirement starts when the product is removed from bonded premises. If your product was labeled and removed from bonded premises before the start of this year, it is not required to have the tax class statement.
If your cider was labeled in 2018 but wasn’t removed from bonded premises until 2019, the cider tax class statement must be present on the label. The TTB will allow a sticker with the statement to be applied to the label to be in compliance. Read more in TTB’s Industry Circular 2017-2.