How to owe nothing on your federal tax return

By Amy Fontinelle

Do you struggle to pay your taxes in April? Or, do you have the money, but hate waiting until your forms are filled out before you know how much you'll have to pay? Many people don't realize that it is fully within their control to determine how much they will owe or how much of a refund they will receive at tax time.

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The way you fill out the W-4 form that you turn in to your employer determines how much tax you will have withheld from each paycheck, which determines how much you will ultimately owe or be refunded in April. What you may not know is that it's possible to submit a new W-4 form to your employer whenever you want -- it's not a one-time thing that you do when you first get the job. (For more on income taxes, see our Income Tax special feature.)

If you don't want to owe anything, but you also don't want to overpay taxes and give an interest-free loan to Uncle Sam, read on to find out how to get your tax bill or refund closer to zero before tax times approaches.

Determine Your Total Tax Liability

Your personal situation will determine how accurately you can calculate your total tax liability for the year. If you are a salaried employee with a steady job, it's relatively easy, because you can predict what your total income for the year will be. If you're an hourly, seasonal or self-employed worker, make an educated guess based on your earnings history in your current line of work. (For more information, read Common Tax Questions Answered.)

You have three options for calculating your tax liability:

1) Online Paycheck Calculator

Online paycheck calculators can be found easily with a simple Internet search. By entering your state, the number of allowances you entered on your W-4 and your annual income, the calculator will tell you your total federal tax liability for the year. This method is very simple, and the result will be pretty accurate, but it won't be perfect -- depending on a few factors, it could be off by a few hundred dollars.

2) IRS's Tax Withholding Calculator

The tax withholding calculator can be found on the Internal Revenue Service website. This calculator is particularly useful for people with more complex tax situations. It will ask about factors like your eligibility for child and dependent care tax credits, how much you have contributed to a tax-deferred retirement plan or health savings account (HSA) and how much federal tax you had withheld from your last paycheck. Based on the answers to your questions, it will tell you how much federal tax it expects you to owe at the end of the year, what you have paid so far and how much you will owe or be refunded. (To read more about these credits, see Give Your Taxes Some Credit.)

3) Sample Tax Return

If you have tax software or know how to fill out a 1040 form yourself, you can fill out a sample tax return. This will give you the most accurate picture of your end-of-year tax liability. The only thing that can make it inaccurate is that you will most likely be using last year's tax software or last year's 1040. However, if you want to do a little online research, you can usually find out what things have changed from the previous year, such as the new standard deduction amount. Filling out a sample return is also ideal for people who itemize deductions, such as homeowners or those who are self-employed. (Mastering these fundamentals now will take the stress out of tax season. Read more in Next Season, File Taxes On Your Own.)

Determine Your Tax Withholding

Once you know the total amount you will owe in federal taxes, you'll need to figure out how much you need to have withheld per pay period to get to that total by December 31.

If you haven't received any paychecks or pay stubs yet, just divide your total tax liability for the year by the number of paychecks you receive. Then, compare that amount to the amount that is withheld from your first paycheck of the year.

• If not enough tax is being withheld, the easiest way to fix the problem is to fill out a new W-4. On line 6, which says "additional amount, if any, you want withheld from each paycheck," fill out the difference between what you should be paying each pay period and what you're actually paying. You could also decrease the number of allowances you claim, but the results won't be quite as accurate. And, you don't have to wait for your employer's HR department to hand you a new W-4 form -- just print it out yourself from the IRS's website. (For more ways to fill out your W-4 for deductions, read Payroll Deductions Pay Off.)
  
  
• If you've overpaying, and you want to get some of that extra money back each pay period try increasing the number of allowances you claim. It won't match the worksheet, but that doesn't matter. You can claim seven allowances even if the W-4 worksheet suggests you should only claim two, as long as you'll have paid at least 90% of your federal tax liability by December 31. (If you underpay, you'll owe penalties and interest.)
  
  If it's not the beginning of the year, you'll need to compensate for all the previous pay periods when you were over or underpaying your federal tax by filling out a new W-4 to adjust your withheld amount up or down for the rest of the year. Then, the following January, you'll need to fill out a new W-4 again, or else your amounts will be off for the New Year. (Finding out that you owe money when you were expecting a refund is a nasty shock. If this happened to you, read how to bounce back in Top 9 Solutions To An Unexpected Tax Bill.)
  
  
• The basic way to resolve the under or overpayment problem is the same, but instead of dividing the amount you'll owe for the whole year by the number of paychecks you receive, you'll need to figure out how much you've paid in federal taxes so far (your paystub may have a running total; if not, ask your HR department). Subtract that amount from what you owe, then divide the result by the number of pay periods remaining for the year. The final number is how much federal tax you need to have withheld from each paycheck. If you've been underpaying, a simple subtraction calculation will show you how much extra you need to pay each month. (For more on prepaying taxes, read Money Saving Year-End Tax Tips.)
  
  
• Figuring out the reverse is trickier, though. There is no simple way to do this; the best way to figure it out is to plug different numbers of federal allowances into a paycheck calculator until it spits out the amount closest to the calculated federal tax you want to be paying each pay period.

Remember, if you're self-employed, have fluctuating income because you're an hourly or seasonal worker, have multiple jobs or itemize your deductions, things get considerably more complicated. You probably won't be able to make sure you owe nothing on your taxes with 100% accuracy, because your income and expenses will change throughout the year, but following these steps may help you get closer to a reasonable number. You can always redo the calculations described above two or three times a year as your income picture evolves. (For more on how itemized deductions can impact your taxes, read An Overview Of Itemized Deductions.)

Conclusion

It sometimes takes considerable effort to figure out what amount you should really have withheld from each paycheck, especially if it's not the beginning of the year. However, a couple of hours now can either increase your monthly cash flow for the rest of the year or save you from an unexpected bill at tax time. 

Read about why having money now is more valuable than having the same money in the future in Understanding The Time Value Of Money.
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Amy Fontinelle is a financial journalist and editor for a variety of websites, public policy organizations, and book publishers. She has written hundreds of published articles and blog posts on topics including budgeting, credit management, real estate and investing. Her articles have been featured on the homepage of Yahoo! and on Yahoo! Finance, Forbes.com, SFGate.com and numerous local news websites.

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