回複：Question about TAX underwithholding

正如stp所說，是有特例，如果滿足，不用繳納罰款。比如你上一年度12個月應稅額為3000元，今年你的抵扣withhold為3100元，而現在在return上算出你今年的應稅額為7100元，即你說的短了4000元。在這種情況下，即已抵扣的3100大於去年全年的應稅額，你不用付罰款。具體參看irs.gov的下麵描述。

Generally, you should make estimated tax payments if you will owe tax more, than an amount specific by law, after withholding and credits, and the total amount of tax withheld and your credits will be less than the smaller of:

90% of the tax to be shown on your current tax return, or 100% of the tax shown on your prior year's tax return, if your prior year's tax return covered all 12 months of the year. However, if your prior year's adjusted gross income exceeded a certain amount based on your filing status, then you must pay 110% instead of 100% of last year's tax. (Note: the percentages change depending on the tax year. Refer to Chapter 2 of Publication 505, Tax Withholding and Estimated Tax.)