In the previous year we owed because my spouse claimed 4 allowances in her W4. We made sure that we don't owe again by claiming zero in both of our W4s. We just found out that we still owe in 2018 tax return without having any other source of income and having 2 kids. Is that possible? We are thinking of hiring a tax guy and let go of turbotax in future tax filings.
I believe it is possible to claim zero allowances and still owe income tax. When the tax law changes were implemented last year the withholding tables were reduced to accommodate the reduction of tax rates, so it is possible that tax withholding was reduced enough to create a balance due even if zero exemptions were claimed. To avoid this situation in the future, taxpayers can request employers to withhold additional amounts over and above the amounts indicated on the tax withholding tables.