Taxpayers who have income from which taxes are not withheld are generally required to pay quarterly estimated tax payments to the Internal Revenue Service.

What kind of income doesn’t provide witholding of income taxes?

Well, for one, alimony.

That’s right.

Alimony is generally included as taxable income for the recipient.

But no taxes on alimony income are withheld.

Therefore, in order to avoid penalties and interest, quarterly estimated taxes should be paid on it.

(Unless taxes are withheld on other income, in which case the amount of withholding can be adjusted upward to, in effect, withold sufficient taxes for the alimony.

Read more in this BankRate article: The skinny on paying estimated taxes.