How do I enter my income on a quarterly basis?

Need more details. TurboTax is for reporting your total income for the entire tax year. So it's not understood what you're trying to do. Are you trying to reduce the quarterly tax underpayment penalty maybe?

YES, I have a penalty on my state return

I can't help with state stuff. But like I said, more details are needed. Before anyone else reading your post can even offer help, you might want to share which of the 37 states that tax personal income, you're dealing with.

2018 Oregon State return.  2018 state quarterly tax payments subject to penalty.  How do I enter state 2018 pymts and income on a quarterly basis for the penalty calculaton.  A Large percentage of our income was earned in the fourth quarter so there should be no penalty.

You can make estimated payments for 2019. This will count towards any tax due.

You can print next year's estimated tax vouchers (Form 1040-ES) in your 2018 program:

1. When in your account, select the Take Me to My Return button on the main screen.
2. Search for 1040-es (exact phrase) in your program's search box, located in the upper right corner.
3. Select the Jump to 1040-es link in the search results.
4. Answer No to the W-4 withholding question to start the estimated payment calculations interview.

• You'll be asked a series of questions about your 2019 income. Answer them as best you can.

1. When you get to the Print Vouchers? screen, answer Yes. They'll print with your federal return.

• If you get the No Payments screen instead, you don't need to make 2019 estimated payments based on what you entered.