There are some jobs that help you earn income long after the project is done. Residuals are the payments you earn every time your work is used or licensed. How much you earn in residual payments depends on the work, your initial work contract and how much the distributor is making off of the licensing. Most careers that offer you residual income are in the entertainment industry and have to do with film, music and TV production.
Musicians earn several different types of income, one of which is residuals from songs that are licensed to TV shows, commercials and films. When a musician's music is used in this capacity, there is often a licensing fee that is paid to the artist. After the fee, the residuals are collected when the production is sold as a DVD or in digital format, rented or shown on TV. The amount a musician earns for this is a very small percentage of the total residuals for the project, but if the production is popular, such as a hit movie, the few cents that the musician earns can quickly add up.
Actors receive residual payments from projects long after the initial release. Rather than having to attempt to collect these payments themselves, professional agencies such as the Screen Actors Guild collect residual payments for actor members and distribute them on a regular basis. Background, or "extra" actors, do not receive residuals. To be considered for residual distribution for the production, you have to be considered a principal actor, which means you're featured in the credits and have at least a small speaking role in the film or TV show. Actors earn residuals when their show or film is sold as a DVD or digital download, or is put into syndication on a cable or broadcast TV outlet.
A movie or TV producer earns residual income in much the same way as an actor, when the project is rented or sold into syndication. The difference is that the producer is a behind-the-scenes person who receives a cut of the residual profit based on his personal investment in the film. Often, the percentage of the total residuals earned for a project that a producer gets is based on how much money he invested in the production initially. This percentage may also be affected by the conditions that the producer agreed to in his contract to be a part of the project's production.
There are several different types of writers, but only one type earns residual income. Screenwriters and TV writers are eligible to earn residuals off of past projects that are licensed or sold. Professional agencies such as the Writers Guild of America track and collect residual payments on behalf of writers. These payments are dispersed to the writer usually once per quarter. For a writer, residuals are comparable to receiving royalties, though they are not the same thing. Royalties are the percentage that a writer earns on a published work, such as a book, and are based on the selling price of the work. The writer's residual payments are a small percentage that is based on the total amount of residual profit income earned from a work such as a film or TV episode.