Shadow economies are usually associated with illegal activity, such as drug dealing and off-the-books work including personal and domestic workers, such as housekeepers and nannies.

The jobs are in service industries from small food establishments to landscaping. Even the arts and culture industry is not immune to working off the books in areas of music and entertainment.

It also includes firms that hire hourly or day construction labor, information technology specialists and Web designers. Many who have a job that doesn't pay enough take another one that pays under the table.

The US. Economy of 2013 includes an estimated $2T in underground cash activity plus an unknown amount of barter. Academic estimates suggest 75% of the shadow economy is generated by black markets including drugs (legal drugs illegally obtained make up a third of this figure), prostitution, gambling, etc. The remaining 25% comes from off the books payments for otherwise legal activities.