Calculating estimated tax payments on a quarterly basis can be arduous depending on the financial activity of the taxpayer that year. We essentially need to do the whole tax return which requires a heavy lift in data collection and making assumptions.
Safe-Harbor: Pay 110% of the previous year's taxes if your AGI exceeds $150,000 or $75,000 for MFS.
Do you need to update your W-4? Self-check calculator: https://www.irs.gov/individuals/tax-withholding-estimator
If you didn’t pay enough tax throughout the year, either through withholding or by making estimated tax payments, you may have to pay a penalty for underpayment of estimated tax. Generally, most taxpayers will avoid this penalty if they owe less than $1,000 in tax after subtracting their withholdings and credits, or if they paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller.
https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes
State of California: https://www.ftb.ca.gov/pay/estimated-tax-payments.html
We include the estimated tax worksheets in vouchers in tax preparation. However, people often do not notice them. Please contact us if you cannot find them in your tax return.