Obviously, you want to make sure that all tenants have the income to pay the rent each month.  Call the prospective tenant’s employer to verify income and length of employment. (some employers require written authorization from the employee) If you question the income information you get by phone, for example, you suspect a buddy is exaggerating on his/her behalf, ask applicants for recent paycheck stubs.

It is also reasonable to require documentation of other sources of income such as: social security, disability, workers compensation, public assistance, child support or alimony.  To evaluate the financial resources of self-employed persons or someone who is not employed, ask for copies of recent tax returns or bank statements.

TIP
How much income is enough? Think twice before renting to someone if the rent will take more than one-third of their income, especially if they have a lot of debts.