If you are self-employed or work as a non-employee contractor, your earnings are not subject to federal or state withholding requirements. Since the U.S. tax system is a pay-as-you-go system, the Internal Revenue Service expects you to make quarterly estimated tax payments throughout the year, rather than pay your full tax due when you file your federal return. It can be difficult to correctly estimate these payments, particularly when your income fluctuates, but underpayment of estimated taxes can result in a penalty. If you are subject to self-employment tax, add it to the base tax liability.
Make quarterly estimated tax payments using this form. The due dates are April 15 for taxes on income earned during the first quarter of the year, then June 15, Sept. 15 and Jan. 15, or the next business day. If you file your full-year return by April 15 you do not need to make a fourth-quarter estimated payment. You may pay the full amount in any combination of payments, spread out over the year.
Regular Installment Method
The IRS penalizes taxpayers who have a balance due of over $1,000 when they file returns, unless you've paid at least as much tax during the year as you owed the previous year. The easiest way to avoid such a penalty is to pay what you owed last year, in four quarterly payments sent in with Form 1040-ES (see Resources). If your income or deductions are substantially different from last year, another method may be more advantageous.
Annualized Installment Method
If your earnings or deductions will be drastically different from the previous year, or if your earnings fluctuate throughout the year, estimate your profit separately each quarter. Add up your income and subtract your deductible expenses for the quarter. Calculate that quarter's estimated tax payment based on your expected tax bracket, included in worksheets with Form 1040-ES. You'll calculate the tax liability for the year-to-date and can adjust the amount paid if you find you are ahead or behind the amount owed.
Include other sources of income such as interest, dividends or capital gains, and deductions for exemptions, standard deductions or any tax credits for which you may qualify. Using the detailed estimated worksheets provided by the IRS will allow you a relatively accurate method for both estimating and paying your quarterly payments. Married taxpayers will need to incorporate a spouse's income and withholding when calculating estimated taxes.
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