Do I claim a child as my stepson, if he's lived with me all year, am not married to his mother, she don't work

[rfisk_78]

I support him 100 percent, and neither of his blood parents can claim him

[SamiaI]

You can claim the child as a Qualifying Relative, as Other (not as step-child). See screenshot below.

There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative").  Only a QC qualifies a taxpayer for the Earned Income Credit 

 An unrelated person can still be a Qualifying relative dependent, if 

1. he lived with the taxpayer ALL year and

2. His/her gross taxable income for the year must be less than $4,050 (2016-17) and

3. The taxpayer must have provided more than 1/2 his support 

Read TurboTax Faq below for more information regarding dependents:

https://ttlc.intuit.com/replies/5187060