why am I having to pay estimated California State taxes for 2025 this year? I never have before.

[simesters]

How have the rules changed for requirements to pay estimated taxes for 2025?

[SharonD007]

TurboTax generates estimated tax payment vouchers if you are self-employed or there isn't enough withholding from your income. You don't have to make these payments— TurboTax calculated the estimated tax payments based on your information. 

You can increase the amount your employer withholds from your pay check or If you’re self-employed, you’ll probably have to pay estimated taxes.

Refer to CA FTB Estimated tax payments for more information.