Trying to confirm California estimated taxes Safe Harbor...100% or 110% (what is my CA AGI?)

[befuddled4]

I am trying to figure out what my estimated taxes (or withholding) should be for California state. I want to avoid penalties so I am looking towards the Safe Harbor rules.

For single, I see the Safe Harbor is 110% of last year's taxes if AGI is >= $150,000, or 100% of last year's taxes if AGI is < $150,000.

My confusion is that my Federal AGI is >= $150,000 for last year, but I had a whole bunch of US Treasury Interest which dropped my state taxable income well below $150,000. The TurboTax summary page shows me this California "Taxable Income" figure which comes from Line 19 on my Form 540 Side 2, but I am unclear if this is the official (California AGI?) number I am supposed to measure against for Safe Harbor. If I can use this number, then I only need to pay 100% of last year's taxes instead of 110%.

I want to make sure I am using the right number so I don't underpay my CA state estimated taxes. I also want to make sure I am not supposed to use my Federal AGI for California Safe Harbor calculation.

Thank you

[MaryK4]

The California safe harbor applies to the California adjusted gross income.  Source: Estimated tax payments | FTB.ca.gov

[befuddled4]

So where do I find my California Adjusted Gross Income figure?

[MaryK4 · Accepted solution]

On the CA 540, it will be Line 17.  @befuddled4