"Generally, you do not have to make estimated tax payments if the total of your California withholdings is 90% of your required annual payment. Also, you do not have to make estimated tax payments if you will pay enough through withholding to keep the amount you owe with your tax return under $500 ($250 if married/registered domestic partner (RDP) filing separately). "
So if on your 2020 CA return, you owed more than $500 or you failed to pay 90% of the tax due by the end of the year, TurboTax would produce the 540-ES.
Please note that sometimes taxpayers get these estimated tax forms when they had a unusual income situation, like a large stock sale with no corresponding withholding. If 2021 will not be like 2020, then you might not have to make any estimated tax payment at all. Doing estimated tax payments is trying to have you avoid any penalties for the under payment of estimated tax, but the numbers from TurboTax are just that - an estimate, based on your 2020 return.
You can find blank copies of the 540-ES at this at this FTB website.
Alternatively, you might look at the options to pay the CA FTB online.
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