One of the easiest ways for someone to commit fraud is to prepare employment tax returns for farmers and handle the remittance of the funds to the IRS and appropriate state authorities. What will happen is the farmer transmits the funds to the third-party preparer assuming that person will then remit the funds onto the appropriate party. After several months or right after the first of the year, the farmer will get a letter from the IRS asking where the funds are that were reported on Form 943, etc.
To prevent this type of fraud, it is extremely important to either completely control the process of remitting these funds to the IRS (i.e. do it yourself) or make sure you are dealing with a reputable firm. The Treasury Department just issued a report indicating the safeguards that the IRS and employers should implement. There are good suggestions in the report and if you are in this situation, I would suggest skimming through the report.