Can I get back money the IRS took out of tax return stating I couldnt claim my 16 year old that lives at home and goes to school

It depends.  You will need to contact the IRS and determine why they disallowed your claiming your child.  Once you speak to the IRS you may need to provide additional information/documentation, and/or file an amended return.  But you will need to start by contacting the IRS. 

 

Before you call, make sure you know or have the following information handy:

• Social Security cards and birth dates for those who were on the return you are calling about
• An Individual Taxpayer Identification Number (ITIN) letter if you don’t have a Social Security number (SSN)
• Filing status – Single, Head of Household, Married Filing Joint or Married Filing Separate
• Your prior-year tax return. We may need to verify your identity before answering certain questions
• A copy of the tax return you’re calling about
• Any letters or notices we sent you

IRS phone numbers 

Customer service representatives are available Monday through Friday, 7 a.m. to 7 p.m. local time, unless otherwise noted. Residents of Alaska and Hawaii follow Pacific time. Puerto Rico phone lines are open 8 a.m. to 8 p.m. local time.

Individuals:

800-829-1040

Businesses:

800-829-4933

People with hearing impairments:

800-829-4059 (TDD) See Tax Topic 102.

Exempt organizations, retirement plan administrators, and government:

877-829-5500 (Monday through Friday, 8 a.m. to 5 p.m. local time)

Estate and gift:

866-699-4083 (Monday through Friday, 8 a.m. to 4 p.m. Eastern time; Forms 706 United States Estate (and Generation-Skipping Transfer) Tax Return and 709, United States Gift (and Generation-Skipping Transfer) Tax Return only)

Excise tax function:

866-699-4096 (Monday through Friday, 8 a.m. to 6 p.m. Eastern time)

If you live outside the United States

Hours of availability vary by location. Please see our International Services page.

Face-to-face assistance

In certain areas, the IRS has local offices you may visit to receive assistance. All offices operate by appointment.

this might not be the reason, but ask your son if he filed his own return and did not indicate he could be claimed by another taxpayer (you) as a dependent.