Retirement tax questions

Yes, you can be penalized.  The IRS assumes that all income is paid out evenly over the year, and all taxes should be paid evenly over the year, either via withholding or via quarterly estimated payments.  If you have a lump sum of income at the end of the year, the IRS will assume that a quarterly payment was due April 15, June 15, and August 15 (in addition to a final payment due January 15, 2025) and you can be assessed an under-payment penalty even if you pay in full when you file.

 

You can partly overcome this by including form 2210 with your tax return (to calculate the penalty) and use the optional annualized method.  This allows you to show that your income was irregular, and that your tax payments and withholding in each quarter were appropriate for the amount of income in that quarter.  However, this won't fix your entire problem, because even if you show a lump sum IRA withdrawal in the 4th quarter and a corresponding 4th quarter estimated tax payment, you will still be under-withheld on your social security for all 4 quarters.

https://www.irs.gov/payments/underpayment-of-estimated-tax-by-individuals-penalty

https://turbotax.intuit.com/tax-tips/irs-tax-forms/what-is-form-2210/L2z0haVWb#%23

 

I suggest you adjust your tax withholding from social security so that it covers the highest tax you might reasonably pay on your social security.  For example, an average middle class single adult will be between 12% and 22% tax on 85% of their social security, depending on the amount of the IRA withdrawal.  So you might choose to have 15% or 18% of your social security withheld each month.  Then when you make your IRA withdrawal, you can perform an estimated tax calculation and pay any lump sum tax you might owe, and include form 2210 with your return.   If you overestimate the payment or withholding, you will get the difference back as a tax refund.

 

You can also use various withholding estimators including this one at the IRS.

https://www.irs.gov/individuals/tax-withholding-estimator

 

Plug in your basic information, and run different scenarios with different IRA withdrawals, to get a feel for the range of tax you should have withheld monthly to cover your taxes for the year.