you can rest assured Mom and Dad will find out about the marriage eventually. But it won't be from the IRS directly per-se. Remember, after marriage you have to update your information with the Social Security Administration by visiting your local SSA office. The IRS pulls their data from the SSA every year, which will be around Dec 2018 for the 2018 taxes. So the name change will be reflected, and when the SSN doesn't match up with the last name on your parent's return, they're gonna know something's up. If you are in fact a college student, then you can expect all financial support to be cut off once they find out, since they will not be able to claim you (or more importantly your education expenses) on their 2019 return because you're married for the entire tax year.
