Cap gains if I seller finance

[Glenn Smits]

Lets say I have a paid off rental worth 200k and I have depreciated it all the way and want to sell it. I will need to pay cap gains. 1031 exchange does't work for me because of timeframes and a competitive market. 

How do the cap gains work if I seller finance? I would take a down payment of 20% and then have a mortgage term of 15 years. Would I need to pay cap gains on the 20k that I get as a down payment and then pay quarterly as I receive mortgage payments over time?

This is in New York state