How to report my amended tax payment?

I amended my tax return of year 2015 in year 2018, and I made extra tax payment to CA, e.g. $500. later I also paid some interests and penalties.

When I file my tax return of year 2018, I input my CA tax refund of year 2017 e.g. $2000, because I use itemized deduction.  My question is: how shall I report $500 in TurboTax in my 2018 return, so I want to reduce the money I get from CA. e.g. I want to say I actually only get $1500 net from CA (2000 - 500 = 1500).

Thanks for your help!