"my GF let her parents claim my son as a dependent"
There's nothing fraudulent or illegal here. The GF's parents claimed your GF as their dependent and they were entitled to do so. (unless you can prove otherwise) Because of that, the GF could not claim any dependents of her own. Because the GF is not married, the GF has the say when it comes to her child and taxes. Not you. But that was only for the 2016 tax year. For the 2017 tax year, here's how this works.
" We took the deal. It’s 2018 and I still haven’t received my car "
That has nothing to do with taxes. That would be a legal or personal matter. We don't give legal advice in this forum.
" I no longer live with my Gf and my son"
Then when it comes to taxes, you have no claim for 2018. But for 2017, there are rules that apply. In order to claim the GF as your dependent on your 2017 tax return, the following criteria for "qualifying relative dependent" must be met. All of it.
- *You* must not qualify to be claimed as a dependent on anyone else's tax return. (such as your parent's). Your parent's don't qualify to claim you if you were *NOT* a full time student for any one semester in 2017 *AND* you earned more than $4,050 of gross taxable income.
- She must have not qualify to be claimed as a dependent on her parent's return. Weather she's actually claimed or not doesn't matter. She must not "qualify" to be claimed on her parent's return.
- She must have lived with you all year (all 365 days of it) as a member of your household. (I gather since you live with your parent's, you don't have a household)
- She must not have gross taxable income in 2017 of more than $4,050
- You must have provided more than half of her support for the entire year.
If all the above conditions are not met, you can not claim your GF as a dependent on your 2017 tax return. Period.
IN order to claim your son as a dependent on your tax return the following "qualifying child dependent" rules must be met. All of them.
- Must have lived with you as a member of your household for more than half the year. That would mean the child slept at your house for more than 182 nights of the year. The IRS counts the days, by the number of nights the child slept over. Not by the number of days the child may have visited you. But if you lived with your parents in 2017, you don't have a qualifying household.
- The child did not provide more than half of their own support. ( I doubt a 1 year old could do that.)
- The child must not be the qualifying child of any other tax payer. (In your case, the baby may be the qualifying child of your GF, or possibly her parent's if the child lived in their household more than half the year.)
I would suggest you seek legal advice. Based on your statement of "I no longer live with my GF and son" you should expect legal actions against you for child support. As for getting custody of your son, the only way I've ever known a judge to take a child from it's mother is if the mother is either dead, incarcerated or found guilty of some other highly serious criminal offense such as something dealing with drugs and drug trafficking. So you really need to retain legal counsel and be ready. Especially once you are gainfully employed if you're not already.
Overall though, I would expect you would not have an problems with child support. It is your son after all and I have no doubt you want the best for him. But sometimes mother's can get over zealous with the monthly amount, and you both may need the courts to settle the matter in accordance with your state's laws on this.