Why is my OK State tax so different from '17 to '18?...'17 taxable income $81,321 Tax $2,174 Withheld $2,185 $10 Refund: '18 Income $85,197 Tax $3,904 WH $3,089 Owe $815

No state tax increase I know of, yet tax due increased 80% when virtually all info is same year to year except income up less than 5%.