The Internal Revenue Service this week issued its annual "Dirty Dozen" ranking of tax scams the agency says tend to surface around tax season each year."Taxpayers should be careful and avoid falling into a trap with the Dirty Dozen," said IRS Commissioner Doug Shulman in a statement. "Scam artists will tempt people in-person, on-line and by e-mail with misleading promises about lost refunds and free money. Don't be fooled by these scams."MORE: 9 best practices for successful IT projectsHere's the Dirty Dozen list from the IRS:Identity theftThe IRS is increasingly seeing identity thieves looking for ways to use a legitimate taxpayer's identity and personal information to file a tax return and claim a fraudulent refund.In response to growing identity theft concerns, the IRS has embarked on a comprehensive strategy that is focused on preventing, detecting and resolving identity theft cases as soon as possible. In addition to the law-enforcement crackdown, the IRS has stepped up its internal reviews to spot false tax returns before tax refunds are issued as well as working to help victims of the identity theft refund schemes.MORE: IRS: Top 10 things every taxpayer should know about identity theftAn IRS notice informing a taxpayer that more than one return was filed in the taxpayer's name or that the taxpayer received wages from an unknown employer may be the first tip-off the individual receives that he or she has been victimized.The IRS has a robust screening process with measures in place to stop fraudulent returns. While the IRS is continuing to address tax-related identity theft aggressively, the agency is also seeing an increase in identity crimes, including more complex schemes. In 2011, the IRS protected more than $1.4 billion of taxpayer funds from getting into the wrong hands due to identity theft.PhishingPhishing is a scam typically carried out with the help of unsolicited email or a fake website that poses as a legitimate site to lure in potential victims and prompt them to provide valuable personal and financial information. Armed with this information, a criminal can commit identity theft or financial theft.If you receive an unsolicited email that appears to be from either the IRS or an organization closely linked to the IRS, such as the Electronic Federal Tax Payment System (EFTPS), report it by sending it to email@example.com.It is important to keep in mind the IRS does not initiate contact with taxpayers by email to request personal or financial information. This includes any type of electronic communication, such as text messages and social media channels. The IRS has information that can help you protect yourself from email scams.Return preparer fraudAbout 60% of taxpayers will use tax professionals this year to prepare and file their tax returns. Most return preparers provide honest service to their clients. But as in any other business, there are also some who prey on unsuspecting taxpayers. Questionable return preparers have been known to skim off their clients' refunds, charge inflated fees for return preparation services and attract new clients by promising guaranteed or inflated refunds. In 2012, every paid preparer needs to have a Preparer Tax Identification Number (PTIN) and enter it on the returns he or she prepares.Signals to watch for when you are dealing with an unscrupulous return preparer would include that they:aC\/ Do not sign the return or place a Preparer Tax identification Number on it.aC\/ Do not give you a copy of your tax return.aC\/ Promise larger than normal tax refunds.aC\/ Charge a percentage of the refund amount as preparation fee.aC\/ Require you to split the refund to pay the preparation fee.aC\/ Add forms to the return you have never filed before.aC\/ Encourage you to place false information on your return, such as false income, expenses and\/or credits.Hiding income offshoreOver the years, numerous individuals have been identified as evading U.S. taxes by hiding income in offshore banks, brokerage accounts or nominee entities, using debit cards, credit cards or wire transfers to access the funds. Others have employed foreign trusts, employee-leasing schemes, private annuities or insurance plans for the same purpose.While there are legitimate reasons for maintaining financial accounts abroad, there are reporting requirements that need to be fulfilled. U.S. taxpayers who maintain such accounts and who do not comply with reporting and disclosure requirements are breaking the law and risk significant penalties and fines, as well as the possibility of criminal prosecution. Since 2009, 30,000 individuals have come forward voluntarily to disclose their foreign financial accounts, taking advantage of special opportunities to bring their money back into the U.S. tax system and resolve their tax obligations. And, with new foreign account reporting requirements being phased in over the next few years, hiding income offshore will become increasingly more difficult.The IRS has collected $3.4 billion so far from people who participated in the 2009 offshore program, reflecting closures of about 95% of the cases from the 2009 program. On top of that, the IRS has collected an additional $1 billion from up front payments required under the 2011 program. That number will grow as the IRS processes the 2011 cases."Free money" from the IRS and tax scams involving Social SecurityFliers and advertisements for free money from the IRS, suggesting that the taxpayer can file a tax return with little or no documentation, have been appearing in community churches around the country. These schemes are also often spread by word of mouth as unsuspecting and well-intentioned people tell their friends and relatives. There are a number of tax scams involving Social Security. For example, scammers have been known to lure the unsuspecting with promises of nonexistent Social Security refunds or rebates. In another situation, a taxpayer may really be due a credit or refund but uses inflated information to complete the return.False\/inflated income and expensesIncluding income that was never earned, either as wages or as self-employment income in order to maximize refundable credits, is another popular scam. Claiming income you did not earn or expenses you did not pay in order to secure larger refundable credits such as the Earned Income Tax Credit could have serious repercussions. This could result in repaying the erroneous refunds, including interest and penalties, and in some cases, even prosecution.False Form 1099 refund claimsIn this ongoing scam, the perpetrator files a fake information return, such as a Form 1099 Original Issue Discount (OID), to justify a false refund claim on a corresponding tax return. In some cases, individuals have made refund claims based on the bogus theory that the federal government maintains secret accounts for U.S. citizens and that taxpayers can gain access to the accounts by issuing 1099-OID forms to the IRS.Frivolous argumentsPromoters of frivolous schemes encourage taxpayers to make unreasonable and outlandish claims to avoid paying the taxes they owe. The IRS has a list of frivolous tax arguments that taxpayers should avoid. These arguments are false and have been thrown out of court. While taxpayers have the right to contest their tax liabilities in court, no one has the right to disobey the law.Falsely claiming zero wagesFiling a phony information return is an illegal way to lower the amount of taxes an individual owes. Typically, a Form 4852 (Substitute Form W-2) or a "corrected" Form 1099 is used as a way to improperly reduce taxable income to zero. The taxpayer may also submit a statement rebutting wages and taxes reported by a payer to the IRS. Sometimes, fraudsters even include an explanation on their Form 4852 that cites statutory language on the definition of wages or may include some reference to a paying company that refuses to issue a corrected Form W-2 for fear of IRS retaliation. Taxpayers should resist any temptation to participate in any variations of this scheme. Filing this type of return may result in a $5,000 penalty.Abuse of charitable organizations and deductionsIRS examiners continue to uncover the intentional abuse of organizations, including arrangements that improperly shield income or assets from taxation and attempts by donors to maintain control over donated assets or the income from donated property. The IRS is investigating schemes that involve the donation of non-cash assets -- including situations in which several organizations claim the full value of the same non-cash contribution. Often these donations are highly overvalued or the organization receiving the donation promises that the donor can repurchase the items later at a price set by the donor. The Pension Protection Act of 2006 imposed increased penalties for inaccurate appraisals and set new standards for qualified appraisals.Disguised corporate ownershipThird parties are improperly used to request employer identification numbers and form corporations that obscure the true ownership of the business. These entities can be used to underreport income, claim fictitious deductions, avoid filing tax returns, participate in listed transactions and facilitate money laundering, and financial crimes. The IRS is working with state authorities to identify these entities and bring the owners into compliance with the law.Misuse of trustsFor years, unscrupulous promoters have urged taxpayers to transfer assets into trusts. While there are legitimate uses of trusts in tax and estate planning, some highly questionable transactions promise reduction of income subject to tax, deductions for personal expenses and reduced estate or gift taxes. Such trusts rarely deliver the tax benefits promised and are used primarily as a means of avoiding income tax liability and hiding assets from creditors, including the IRS. IRS personnel have seen an increase in the improper use of private annuity trusts and foreign trusts to shift income and deduct personal expenses.Follow Michael Cooney on Twitter: nwwlayer8 and on Facebook.Read more about wide area network in Network World's Wide Area Network section.