what has happened is that Turbotax has calculated that based on 2022 you will not have enough in withheld income taxes to meet either of the safe harbor tests for avoiding underpayment of estimated taxes in 2023. if it is correct and you wait to pay until 4/15/24 you will be subject to these penalties
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There will be no federal penalties for not paying in enough taxes during the year if withholding
1) and timely estimated tax payments equal or exceed 90% of your 2023 tax or
2) and timely estimated tax payments equal or exceed 100% of your 2022 tax (110% if your 2022 adjusted gross income was more than $150K) or
3) the balance due after subtracting taxes withheld from 90% of your 2023 tax is less than $1,000 or
4) your total taxes are less than $1,000
the lower of 1 or 2 is your required annual income tax payments. 1 is difficult to know until the year end so generally option 2 is the safer option. under the simplified method 25% of the estimate taxes must be paid in each quarter by 4/18, 6/15, 9/15 and 1/15/24. unless you can show otherwise 25% of you annual withholding is assume to occur in each quarter.
failing this and being subject to penalties you can use the annualized installment income method.
this method requires knowing your income and deductions thru 3/31, then 5/31, then 8/31, and finally tear end which should be the same as the tax return. the income is annualized. taxes are computed on the annualized income and then de- annualized. your tax payments for each period must equal or exceed these amounts to avoid penalties.
if you can increase withholding to meet any exception then paying the estimates is not required.
form 2210 page 3
https://www.irs.gov/pub/irs-pdf/f2210.pdf
state laws vary
