Are you sure? Maybe it was a refund being reduced.
Look at your tax return. What lines? What's on lines 24, 28, 30 and 35a or 37 for Tax due. Look over your return. What lines don't you understand?
Before filing, You can preview the 1040 or print the whole return
https://ttlc.intuit.com/community/accessing/help/how-do-i-preview-my-turbotax-online-return-before-f...
