Hello,I made a lump sum income tax payment on April 30/18, as I have a small business. I'm now doing my taxes and not sure where to enter the amount I paid?

You would enter this payment as a tax installment payment when using TurboTax.  Click on Find in the top right-hand corner and type in Tax Installment payment and then click on Go and you will be prompted to enter the appropriate details.

Thanks for the response. However, when I click on tax installments, it asked about how much my "quarterly" installments total. I didn't make quarterly installments. Just one payment. Should I still input my payment there?
Thanks,
Mark

Yes, you should still input your payment under installments eventhough you made the payment as a lump sum payment.

Hi - I am not able to find this line item.  I also paid before the filing deadline and late filing my tax return.  Can you please help me?  Thank you.