Everything seems to always boil down to money.  The heated debate over illegal immigration is certainly no exception.  One of the most contentious issues in the whole debacle is whether illegal immigrants are a drain or a boon to government revenues.

To answer the question, one needs to know how much illegal immigrants contribute to the government through income, sales, property and other taxes, and how much they cost the government by using public services such as education, health care and law enforcement. 

Of course, getting this information is not easy, nor is the data is 100 percent reliable. Those who sit on both sides of the debate have done their research, and both have come out with different answers.

An example:  a 2006 report by the Texas Office of the Comptroller found that the state's estimated 1.4 million undocumented immigrants contributed more in state revenues than they cost in state services during fiscal year 2005.  According to the report, the net gain for the state was $424.7 million.  At the same time, the study showed that in 2005, local governments and hospitals in Texas lost money due to undocumented immigrants, with an estimated net loss of $928.9 million.

To further thicken the plot, the Federation for American Immigration Reform, a non-profit group dedicated to stopping illegal immigration came out with their own study.  Their results contradicted the Texas comptroller's, concluding that illegal immigrants in Texas created an annual fiscal burden of $3.7 billion.

So who is right and who is wrong?

The Congressional Budget Office, which provides Congress with nonpartisan research on budget issues, reviewed 29 such reports published by different organizations over the past 15 years.  In 2007, they concluded that all of the studies are basically off base, saying that they "were not a suitable basis for developing an aggregate national effect across all states," due to a lack of reliable and consistent data and other factors.

Dr. Steven A. Camarota, the director of research at the Center for Immigration studies in Washington, D.C. says that the economic influence illegal immigrants have on a town or state can ebb and flow depending on what public services researchers choose to include in their study.

Some researchers choose only to include direct services such as health care, education, and incarceration.  When this happens, the net fiscal impact "tends to come out more positive," Dr. Camarota said.  But if researchers decided to focus more on the U.S.-citizen children of illegal immigrants and population-based services such as repairs to roads, bridges and other infrastructure, "it turns very negative, very fast," he said.

What is important to note is that, contrary to popular belief, illegal immigrants do give back to the community by paying taxes.  They pay sales and excise taxes for goods and services and property taxes on real estate, whether they rent or own a home.  Those who work legal jobs contribute to the Social Security trust fund by paying payroll taxes.

In addition, the Internal Revenue Service and state officials report than an increasing number of undocumented workers are paying federal and state income taxes using an Individual Taxpayer Identification Number, or ITIN, rather than a Social Security Number.  An ITIN is a tax-processing number issued by the Internal Revenue Service, regardless of a person's immigration status.

"ITINs are used for tax purposed only, and are not intended to serve any other purpose," according to the agency.  "IRS issues ITINs to help individuals comply with U.S. tex laws, and to provide a means to efficiently process and account for tax returns and payments for those not eligible for Social Security Numbers."

While illegal immigrants don't technically have to pay these taxes, more are choosing to do so because they want to be up to date and squared away with the IRS in the event that immigration policy changes and they can safely apply for legal status.

Calculating how much illegal immigrants cost states and municipalities is just as tough as calculating how much they contribute.  Many illegal immigrants take advantage of free public services, from health care to police to schooling for their children.  At the same time, there are likely just as many illegal immigrants out there that don't call the police, go to the hospital, or use other services because they are afraid of being caught and deported.