1. Signing someone else's name on a check
Signing someone else's name on a check is generally considered forgery and would be illegal in most states. But suppose an adult child signs an elderly parent's name because the parent is incapacitated, or a parent signs a child's name because the child is away at college. Guess what? Those signatures are still forgeries, unless a power of attorney is in effect.
2. Using someone else's identity to obtain credit
The use of someone else's name and identity to obtain credit is an obvious no-no. But suppose a parent whose credit has been ruined uses a child's name and identity to open new credit accounts. Illegal? You bet.
3. Lying on a home loan application
Homebuyers and homeowners who want to refinance may be tempted to inflate their income or hide some of their debts to better their chances of receiving a "yes" from the lender. But lying on a loan application is fraud, and lenders do check up on applicants' information.
4. Writing 'bad' checks
Many banks offer overdraft protection that kicks in if you write a check for more than the balance of your account. But writing a check that you know is no good is illegal. The risk isn't negligible: some people do get prosecuted for writing bad checks.
5. Copying U.S. currency
Color printers, scanners and copiers make it surprisingly easy for just about anyone to replicate U.S. or foreign currency. But it is, in fact, illegal to print your own money and try to spend it to buy goods or services.
6. Defacing U.S. currency
U.S. currency isn't designed to be run through the clothes washer, written on or masticated by pets. Yet while accidental damage to currency normally isn't illegal, deliberate defacement is. Federal law prohibits any action that mutilates, cuts, defaces, perforates or glues together U.S. currency or otherwise renders bills unusable.