The filing deadline to submit a 2011 Colorado state tax return is April 18, so if you are not able to file your form before this date, you need to learn how to request an extension. If you file your return after the deadline without an extension, you will be assessed a late filing penalty and compound interest on any outstanding tax balance you have.c  

An extension essentially serves as a way of informing the Department of Revenue that you will be submitting a return this year. If your extension is approved, you will have a new filing deadline of October 18. This will help you to avoid the late filing penalty. However, an extension does NOT apply to any payment due. If you will owe additional tax with your return, this will still be due by April 18.c  

Your first step to getting your Colorado extension is to collect all of the essential tax documents needed to calculate your state tax liability. This will be the same information you will use to prepare your state forms, so keep them in an accessible location. You will need the following: 

1. The earned income you received––If you are employed, this will be the total taxable wages reported to you on Form W-2 or Form 1099. If you are self-employed, this will be the gross earnings you received minus any applicable business expenses.
2. The unearned income you received that is also subject to state tax––Examples of this will include unemployment compensation, lottery winnings and pension payments. See the tax form instructions for complete guidelines regarding taxable income.c
3. Your state income taxes already paid during the year––Employees will use the state taxes withheld as shown on Form W-2. Self-employed individuals will use the estimated state tax payments they have made.
4. A copy of your completed federal income tax return, if you are filing one
   

You will use the amount of your federal taxable income as a starting point for assessing your state taxes owed, so you will need to complete your federal return before you begin this procedure. If you will also be requesting a federal tax extension, you may wish to consult a tax professional to help you calculate your taxable income.c 

To complete the extension payment voucher, you will also need the following:

1. Your Social Security number
2. Your current mailing address
3. The full name and Social Security number of your spouse, if you will be filing a joint tax returnc  

Once you gather your documents, your next step is to get a paper copy of the Colorado tax form to calculate your state tax. If you have access to the Internet, you can download Form 104 "Colorado Individual Income Tax Return" and the accompanying form instructions from the Colorado Department of Revenue website. If you do not have Internet access, you can generally obtain these forms at your local library during tax season.c  

Start by reading the tax instruction booklet carefully, paying special attention to the sections regarding income adjustments you may need to make and state tax credits you may be eligible to claim. Enter the amount of your federal taxable income from IRS Form 1040 on line 1 of your Colorado return. Then make any necessary income adjustments on lines 2 through 13.c 

Calculate your state taxable income on line 14. Then consult the tax tables located in the instruction booklet to assess the state tax owed on your income. Enter this as your tax on line 15. Subtract your eligible tax credits and the taxes you have already paid through withholding or estimated tax payments. What remains will be either a refund on line 43 or a balance due on line 47.c

If you are entitled to receive a refund or if you have a zero balance, you will be able to skip this step. Simply complete your return when you can and submit it to the appropriate address. On the other hand, if you have a balance due, you will need to remit an extension payment before the April 18 filing deadline.

The voucher is entitled Form 158I "Extension Payment Voucher for Colorado Individual Income Tax" and you can download it from the Colorado Department of Revenue website. Complete the voucher by entering your full name and Social Security number, as well as your spouse's if applicable. Write in your current mailing address and the amount of the payment you are making.c  

To remit payment by mail, you have to write out a check or money order for your balance due and enclose it with the voucher. Send both to the address listed on the form by April 18. If you are unable to pay your entire balance at once, send in what you can and contact the Department of Revenue about establishing a payment plan.c 

Once you submit your payment, you should start working on your Colorado state tax return as soon as possible. This will help you to avoid last-minute rushing as the extended deadline approaches.