That's true, but the cliff will still raise EVERYBODY's income tax rate, and the divi from AGNC will also pay at a higher rate, right? So, there is still a benefit to the shareholders to dish out the unpaid divi before EOY to beat the cliff. The benefit is not as big as to other regular divi stock holders, whom will see their tax rate change from 15% up to 44%, but a few % savings nonetheless.
Management has stated numerous times the desire to pay out a CONSISTENT dividend. I suggest you look at the financials statements and realize that if AGNC paid out a special dividend, they would have to drastically cut the dividend next quarter based on the reduced core income.