Entity information:
Note 14 -Income Taxes
 
The following table reconciles our GAAP net income (loss) to estimated REIT taxable income for the years ended December 31, 2017, December 31, 2016 and December 31, 2015.
 
 
For the Years Ended
 
December 31, 2017
 
December 31, 2016
 
December 31, 2015
GAAP net income (loss)
$
181,154

 
$
(45,517
)
 
$
(31,205
)
Book to tax differences:
 
 
 
 
 
Credit Risk and Non-Agency Securities
(68,505
)
 
(60,914
)
 

Interest-Only Securities
1,216

 
(7,818
)
 

Changes in interest rate contracts
(49,930
)
 
179,979

 
177,565

Losses on Security Sales
8,486

 
18,211

 
11,546

Other than temporary loss on Agency Securities
13,707

 
6,540

 

Amortization of deferred hedging costs
(59,930
)
 
(47,952
)
 
(13,731
)
Premium amortization expense on Agency Securities
(468
)
 

 

Bargain purchase price on acquisition of JAVELIN

 
(6,484
)
 

Other
15

 
19

 
17

Estimated taxable income
$
25,745

 
$
36,064

 
$
144,192



Interest rate contracts are treated as hedging transactions for tax purposes. Unrealized gains and losses on open interest rate contracts are not included in the determination of REIT taxable income. Realized gains and losses on interest rate contracts terminated before their maturity are deferred and amortized over the remainder of the original term of the contract for REIT taxable income.

Net capital losses realized
 
Amount
 
Available to offset capital gains though
2013
 
(579,322
)
 
2018
2014
 
(341,850
)
 
2019
2015
 
(5,182
)
 
2020
2016
 
(31,204
)
 
2021


The aggregate tax basis of our assets and liabilities was greater than our total Stockholders’ Equity at December 31, 2017 by approximately $69,175, or approximately $1.65 per common share (based on the 41,877 common shares then outstanding).

We are required and intend to timely distribute substantially all of our REIT taxable income in order to maintain our REIT status under the Code. Total dividend payments to stockholders were $105,289, $126,633 and $182,764 for the years ended December 31, 2017, December 31, 2016 and December 31, 2015, respectively. Our estimated REIT taxable income available for distribution as dividends was $25,745, $36,064 and $144,192 for the years ended December 31, 2017, December 31, 2016 and December 31, 2015, respectively. Our REIT taxable income and dividend requirements to maintain our REIT status are determined on an annual basis. Dividends paid in excess of REIT taxable income for the year (including amounts carried forward from prior years) will generally not be taxable to common stockholders. The portion of the dividends on our common stock which represented non-taxable return of capital was approximately 88.95% in 2017, 81.55% in 2016 and 22.88% in 2015.

Our management is responsible for determining whether tax positions taken by us are more likely than not to be sustained on their merits. We have no material unrecognized tax benefits or material uncertain tax positions.