Jobs for 12 Year Olds That Pay
According to the official website of the government’s youth employment, you can only do certain of jobs if you are under 14.
These jobs include:
- delivering newspapers (the paperboy)
- movies, tv, radio or theater actor or performer
- gathering evergreens and making evergreen wreaths as a homeworker
- work at your own family business as long as it is not as listed as hazardous occupations
The fact now regarding delivering newspaper
It is no longer the paperboy riding bicycle like the old days who deliver the newspaper today, but adults on their cars. 
You can still work as a babysitter now, but soon robots may replace babysitters in the future
Taking care of younger kids may be fun or the contrary, a disaster. You need to know basic knowledge about how to stay safe, how to handle with unwanted behaviors, what to do in case of emergency and how to choose age-appropriate activities.
You can learn the skills from YouTube, blogs, or join babysitting training or lesson. The American Red Cross paid online course for example is designed to youth ages 11 and older to prepare them to be better babysitters. 
How to be an actor or performer?
Justin Bieber’s mom posted his performance video on YouTube when he was 12, started when he sang for a local singing competition. It was actually for their family and friends to see. 
Gathering evergreens and making wreaths… what’s that?
In other words, you gather flowers, leaves, fruits, twigs and other materials to make a house ornament or decoration. Now who would want to do this if we can buy it from the store?
Other jobs not listed above: tutoring, modelling, pet-walking
If you think you are smart and confident, you can ask your neighbors if their kids need private tutoring.
Certain fashion companies might hire you as their model.