If a 3 year window starts after Dec 31st, 2011, does it mean it ends on Dec 31st 2014 or 2015?

Factual Questions
1

IRS Form 8821:

However, you may include
on a tax information authorization only future tax periods that
end no later than 3 years after the date the tax information
authorization is received by the IRS. The 3 future periods are
determined starting after December 31 of the year the tax
information authorization is received by the IRS.

So if they receive it during July, can I put 2012-2015? Or only 2012-2014, as 3 yrs from July 2011 is 2014?

2

The three years would be
2012
2013
2014

So it ends Dec 31st, 2014.

3

I don’t see the line of reasoning that would lead to 2015.