rest is gravy
the rest is (just) gravy
1. The rest (of some project, journey, process, etc.) will be very easy and straightforward to complete or accomplish. They managed to defeat the best team in the league already, but anyone who thinks the rest will be gravy for them is fooling themselves. The biggest issue is getting the servers up and running—after that, the rest is gravy.
2. Any additional elements will be an unexpected or unrequired bonus. Typically said of additional monetary earnings, but often applied in other ways as well. It should be a pretty self-sustaining revenue stream, so once we pay off the initial costs for materials, equipment, and set-up, then the rest is gravy. The most important thing in my eyes is for them to get the characters from the books right in the film. If they do that, then the rest is just gravy to me.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
(the) rest is gravy
Fig. Any additional money received is just an easily acquired bonus. There is some cost involved in buying the raw materials, and the cost of manufacturing is negligible. When we pay off the costs, the rest is gravy.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.