If it says tax due that means you are not getting a refund.  Tax due means you have to pay.  Look at your Form 1040.  What does it say?  

Tax Refund  is shown on line 20----is there an amount on that line?

Tax due is shown on line 23 --- if you have something there that means you need to pay by April 15, 2020.

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

And if you thought a refund was paying a tax due amount:

Your state tax due cannot be paid from your federal refund.

It is not possible to pay your state tax due from your federal refund, nor is it possible to pay a federal tax due from a state refund.  The federal and state treasuries are completely separate from each other.  You may have seen a TurboTax summary of your federal and state amounts that confused you into thinking one was “paying” the other.  It is not.  If you have federal tax due you can pay by mailing your payment with the 1040V voucher, having the payment taken out of a designated bank account, or you can pay directly on the IRS website.

https://www.irs.gov/payments/direct-pay

You must pay your state tax due using the state’s preferred method of receiving payment.  For most states that will be by making a payment to the state’s own tax website, or by mailing a check or money order.

https://ttlc.intuit.com/questions/1900884-what-are-my-options-for-getting-my-state-refund-or-for-pay...