How does Turbo Tax calculate underpayment penalty?

Hi,

 

I knew there is a safe harbor to avoid an underpayment penalty is to:

 

Aim for "100 percent of your previous year's taxes." If your previous year's adjusted gross income was more than $150,000 (or $75,000 for those who are married and filing separate returns last year), you will have to pay in 110 percent of your previous year's taxes to satisfy the "safe-harbor" requirement.

 

My question is:

How do I let Turbo Tax know my previous tax?

 

Thank you in advance for your assistance!

 

Regards,

Avon