So it sounds like you claimed a non-relative as your dependent, and filed as Head of Household, thereby getting the child-related credits such as child tax credit, possible earned income credit, as well as the personal exemption for the dependent? And then you relied on bad advice.."don't send the info or file for that year."
You need to amend your tax returns on which you falsely claimed the child was your nephew. As for whether you could even claim the child as a dependent at all is shaky. Did he live with you the entire year? Did his parent(s) earn more than $4000?
You should actually seek paid local tax advice to straighten this out. Do not go to the same person who advised you to sweep it under the rug and hide from it.
Here is some information on what Head of Household means, and then some information on how to amend.
Am I Head of Household?
https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household
https://ttlc.intuit.com/questions/2900097-what-is-a-qualifying-person-for-head-of-household
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent
To learn more about amending your tax return, please review the information in the following link.https://ttlc.intuit.com/questions/1908543-do-i-need-to-amend-my-tax-return
Click or tap a tax year for specific amending instructions.
· 2016
· 2015
· 2014
· 2013
Related Information:
· What does it mean to "amend" a return?
· Do I Need to Amend my Tax Return?
· Will amending delay my original tax refund?
· What is the deadline for filing an amended return?
· Can I e-file my 1040X to amend my return?