I absolutely agree that we all don't all know everything about taxes.....well maybe a few people in here might (you know who you are! LOL), I certainly don't!  But I always do some research to find my answer before posting here.   

This was one of the big things that changed with the TCJA for 2018, and any continuing education you attended during the year to prepare for the 2018 tax season would have certainly gone over it in detail...if they didn't you should ask for a refund.   

At the very least, you should printout or have a bookmark to IRS Pub 17 https://www.irs.gov/pub/irs-pdf/p17.pdf  Its got all the basics you might need to know for individual tax returns and its FREE!