LOTS of helpful links for entrepreneurs: http://business.usa.gov/
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You can reduce or even eliminate a balance due after filing, by adjusting your withholding amount with your employer or making estimated payments.
IRS Withholding Calculator can help you adjust the amount withheld from your pay by your (W-2) employer, in order to reduce or eliminate your balance due.
Estimated tax is the method you use to pay tax on income that is not subject to withholding, such as self-employment (1099) income.
UNITED TAX SERVICE