the easiest but maybe costliest way to avoid a penalty is that withholding and timely estimated tax payments must equal the lesser of 90% of current year tax or 100% of prior year tax (110% if your prior year agi is over $150K).
under the annualized installment method withholding can be allocated to the actual period it occurred.
the safest method is the prior year tax route. no guessing as to 90% of current year tax but if you have a lot of taxes in the prior year that you won't have in the current year you'll be letting the US Treasury hold your money tax free for an extended period. there is something some taxpayers can do if they can control their withholding. don't pay the estimates. near year-end increase withholding so you meet the 100%/110% test
alternative pay the first couple of estimates and then determine if the others are needed.
