After filing with Turbo Tax, I just received a statement from IRS showing much higher amount owed.

You should get a letter explaining the adjustment. 

I RECEIVED A LETTER FROM THE IRS/STATE

 

 

TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.

 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-audit/turbotax-audit-support/L6AcMoNFD_US_en_US?uid=m5z7by9u

 

 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/internal-revenue-service/got-cp2000-notice-irs/L7Da6em2t_US_en_US?uid=m4of6ngd