I have a small business and I paid Sales & Use Tax in CA. The last period of the year is from Oct, 01, 2018 to Dec, 31, 2018 the due date was January, 21, 2019.

So I paid this taxes in 2019. My question is: to which taxable year should I apply this taxes in my tax return?
Is it for Tax year 2018 even though I paid them in 2019 or is for Tax year 2019 since I paid them in 2019. Any help would be great. Thanks