Father being IRS audited

Why would my dad be audited by the IRS for tax year 2016? If I was a student in 2016 and dependent still. He got a letter stating he is being audited because of false claims that he pays my tuition.

I got married in October 2016 but didn’t file jointly until tax return 2017? I’m so confused.

He said he may be penalized $3,000