I missed second quarter estimate CAN I now have that amount with held from an RMD with drawl and all is OK thanks Frank

[Opus 17]

Yes, having withholding is a very good idea. 

For purposes of avoiding tax penalties, you must pay into the system, either from withholding or estimated payments, an amount that is either:

a. 90% of this years' tax bill

b. 100% of last year's tax bill

c. enough that you owe less than $1000 when you file your return.

If you make estimated payments, they are considered made when you make the payment, and if you miss a payment, you can be assessed a penalty for underpaying the estimate even if you catch up.   However, withholding is assumed to be paid evenly throughout the year.  This means that if you never make an estimated payment during the year, and make a final estimated payment on 12/29, you can be penalized for under-payment; but if you make a withdrawal on 12/29 and have sufficient withholding to cover your taxes, you won't be penalized because you are assumed to have made withholding throughout the year.

It may sound odd at first, but it means that withholding is generally better for avoiding penalties than making payments. 

[dmertz · Accepted solution]

25% of the withholding will be credited to each of the tax quarters, so you might want to have withheld from your RMD twice what you should have paid for your Q2 estimated tax.  The 25% of the withholding credited to Q1 and the 25% credited to Q2 will then cover what you should have paid in estimated tax for Q2.  You can then reduce your Q3 estimated tax payment (if not already paid) and your Q4 estimated tax payment to account for the 25% of the tax withholding that will be credited to each of those quarters.