I have a child which was not claimed as a dependent for last years federal or state return. Can I file an amended return so I have the possibility of receiving a refund?

[bobbyww1967]

This is my wife's child and her EX was gonna claim the child but did not and has agreed to let us claim the child.

[xmasbaby0]

Who does the child live with?

[Carl]

If the child qualifies to be your dependent as clarified in IRS Publication 17 as detailed at <a rel="nofollow" target="_blank" href="https://apps.irs.gov/app/vita/content/globalmedia/4491_dependency_exemptions.pdf">https://apps.irs.g...> then you should amend the return.

[Hal_Al · Accepted solution]

You say " has agreed to let *US* claim the child". That indicates you are filing a joint return with your spouse.  Yes, you can file an amended 2016 return to claim the child. If the child live with you and your spouse for more than half the year, you may claim the child for all tax benefits. If the child lived with you less than half the year, you may claim the child as a dependent and the child tax credit (if child is under 17) but not EIC and day care credit.

Even if you are filing separate from your spouse, you may claim the child, as a step parent is the same as a parent, for tax purposes. 

If the child lived with the "EX",  more than he/she lived with you, you will need to get the ex to sign and give you form 8332, to allow you to claim the child. https://www.irs.gov/pub/irs-pdf/f8332.pdf

[Hal_Al]

Answer edited to include form 8332