It depends on when you paid for the 2016 classes that were billed in 2015.
Check your student school account statement, if you PAID in 2016, you can claim the expenses.
Be sure to keep a copy of your student account statement with your tax records.
If you paid the tuition in 2015, you can only claim the expenses in 2015.
According to the IRS:
“Generally,
the credit is allowed for adjusted qualified education expenses paid in 2016
for an academic period beginning in 2016.....
Prepaid expenses. Qualified education expenses paid in 2016
for an academic period that begins in the first 3 months of 2017 can be used in
figuring an education credit for 2016 only. See Academic period, earlier. For
example, if you pay $2,000 in December 2016 for qualified tuition for the 2017
winter quarter that begins in January 2017, you can use that $2,000 in figuring
an education credit for 2016 only (if you meet all the other requirements). “
CLICK
HERE for IRS Pub 970 Tax Benefits for Education