Is it true that less amount has been withheld from most people's pay checks in 2018? If so, why?

[DDollar · Accepted solution]

There were lots of changes from the Tax Cuts and Jobs Act of 2017, which went in to effect in 2018.  One of those was a change to the tax withholding tables, which resulted in most people having less money withheld from their paychecks.  This was because the tax rates went down, the standard deduction increased, etc.  But the personal exemption was also eliminated.  For many, they are seeing bigger refunds, for many others they are seeing smaller refunds or owing more.

[haghani-p]

Thank you for the thorough response.
I noticed that my 2018 tax was 7000$ less than 2017 but I still owe about 500$ in federal and state taxes. That is despite the fact that I did not change my W4 and I never owed taxes before. Is it because of the changes you mentioned above?