I received approx. $6000 in SS benefits in 2015. I repaid that amt on 12/19/2015 but the certified check was not cashed until 2/12/2016. How do I handle?

My 2015 SSA-1099 did not show this repayment and I had to pay taxes on my benefits.  Can I report this repayment on my 2016 return as negative income under “Other Reportable Income”?