Every time you take a new job, you’re handed a stack of forms to fill out. Included among them will be a W-4. This form tells your employer how much money you want withheld from your paycheck. You can submit a new W-4 to your employer at any time, and you should definitely review your status whenever there are major changes in your life, such as a marriage or a new baby, but you could also benefit from a yearly review of your status.

While you may enjoy getting that big refund check back every spring, remember you’re just getting back your own money. A big refund typically means you simply made a temporary loan to the government by over withholding. It’s your money, the question is do you want it now when you can use it or invest it to create growth, or do you want Uncle Sam to hold it for your until you file your taxes.

On the flip side, if you end up writing a big check to the IRS at tax time you are probably under-withholding. At a certain point the IRS can access a penalty for under-withholding, consult your tax adviser for the specifics.

Getting it just right might be a bit of a challenge, but by taking 10 minutes to utilize the IRS Withholding Calculator you can optimize your withholding so it’s enough to cover your tax obligations and possibly put a little extra in your pocket every week.

Get you documents and information ready before visiting the site. You will need:

Your most recent pay stub and last year’s tax return

Filing status you claimed last year

Number of jobs you currently hold

Number of dependents

Total wages, salaries and tips

Contributions to retirement plans, FSA or HAS

Income tax withheld last tax year

Amount of any unemployment compensation

Income tax withheld from last paycheck

Amount of any non-wage income, such as dividends, interest or alimony

It will give you the option of itemized deductions or standard deductions.

If you wish to use the itemized deductions you will need your medical expenses, taxes paid, interest paid, gifts to charity, casualty and theft loses job expenses and other deductions.

At the end it will estimate your anticipated income tax and project you withholding. Be sure to review the recap information at the bottom to be sure that everything is correct.If you accidentally selected married when your single, entered the wrong birthday, or made any other errors the estimate will be wrong and you will need to start again.