Can I claim my 18 year old son as a dependent who is still in high school and will be attending college later in 2017?

You may be confused by not getting the child tax credit.  You lose the child tax credit when your child turns 17.  You can still claim your 18 year old as your dependent.  If he continues to attend college as a full-time student, you can claim him until he is 24.

What section allows me to claim him ? I have turbotax premium - I can't find the section allowing me to claim him - also I want a phone number I can call to speak to someone like you advertise.

You enter your son as a dependent in Personal Info.  You will put in his name, date of birth, SSN, etc.  You will be asked an oddly worded question about whether he paid over half of his OWN support--say no to that.

send me the call center number like advertised on the box

To call TurboTax customer support
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number">https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number</a>

I ask for a call number like advertised on your box - have never heard back so I'm requesting again send me a contact number like you state on your cover so people will buy your product

Sorry--we do not work for TurboTax, we are volunteers who try to help.  I do not know of any other number to offer to you besides the customer support contact information already provided to you.

So you are telling me you don't work for turbo tax ? You are a volunteer answering questions about people's taxes for them . I find that wrong on so many levels - false advertising for one -

I gave you the contact information for  customer support.  The Answer Xchange is a public user forum where other users of TurboTax can ask or respond to questions. Answer Xchange is NOT customer support nor does it claim to be.   If you do not want to try any of the suggestions here, contact customer support.

Hi My son will be 18 years old in May 2020 and still junior at high school. Can I still claim him and get credit?

Yes of course.   You will not get the child tax credit---you lost that when he turned 17, but you can get the $500 credit for other dependents for him.

https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-credit