Retirement tax questions

I knew we had to claim it this year, but it gives the option to split it between 3 years.  I'm guessing splitting it is also part of that form we're waiting on? Since I didn't see that anywhere else in the turbotax forms when I started my taxes.  I will probably just do it all at once, so I don't forget next year, but for anyone reading, it's nice to know.  Thanks!! 

 

Bill