If your total tax payments are less than your total tax liabilities then you will have taxes owed.
If you didn't pay enough tax throughout the year, either through withholding or by making estimated tax payments, you may have to pay a penalty for underpayment of estimated tax. Generally, most taxpayers will avoid this penalty if they either owe less than $1,000 in tax after subtracting their withholding and estimated tax payments, or if they paid at least 90% of the tax for the current year or 100% of the tax shown on the return for the prior year, whichever is smaller.
Expect your withholding to be less so you have less to pay your tax bill so you may owe taxes if you didn't withhold enough or your refund will just be less. Until you actually put the figures in the return you will not know.
FYI ... NEVER claim exempt on your W-4 if you don't qualify for doing so. If you wind up owing on the return the IRS can hit you up with penalties for doing that ... instead just increase your allowances on line 5 of the W-4 to 10 as that will do the same thing without the possibility of penalty.
And be aware that Personal Exemptions go away as of 1/1/2018.
<a rel="nofollow" target="_blank" href="https://www.irs.gov/newsroom/irs-statement-withholding-for-2018">https://www.irs.gov/newsroom/irs-statement-withholding-for-2018</a>