It depends. The tax reform changes for 2018 impacted tax returns in several ways.
A big change was that the standard deduction was increased significantly in 2018, but this year personal exemptions have been suspended and are no longer taken on a return. Therefore, if you itemized last year an amount close to this year's standard deduction amount, plus had exemptions last year, your taxable income could be greater this year.
Or if you itemized last year and this year, your itemized deductions may have been impacted by the $10,000 minimum allowed deduction for state and local taxes, therefore making your itemized deduction total less for this year and increasing your taxable income.
Another impact may be that less withholding was taken out of your paychecks for 2018 as withholding tables were adjusted and employers took less taxes out for 2018 than in the past.
Any or all of these items could have impacted your return and caused you to owe more when your income scenario was about the same. The best idea is to compare 2018 to 2017 for your adjusted gross income amounts, standard/itemized deductions, taxable income, tax liaibility and withholding amounts to see where the greatest differences are.
Below is more information related to the Tax Reform Changes of 2018:
https://ttlc.intuit.com/replies/6971774
