If you receive W2s, and you likely do, you give those as sole evidence of income reporting and tax remitted for certain forms of income. Some of us have small businesses that receive W2s, some of us receive them from jobs, and some of us receive them for all sorts of other reasons. But, no matter how or why you receive W2s, you should know something about the software that generates these reporting documents. It may report something completely different that the amount of money you actually paid the government. It's possible you have paid more tax (or more has been taken from your check) than is reported in your W2.

I noticed as I was preparing a few tax returns, that amended W2s are quite common. Someone forgot income, screwed up an entry, overstated income, etc. and the original W2 was incorrect enough that the employee brought it to the attention of the employer. "I don't think I actually made X, could you check and correct my W2?" And, sure enough it is often wrong.

The part that should concern you is that I've yet to see an amended W2 that had the same number for "Federal Income Tax Withheld" on the original and the corrected W2. That means the software used to create the W2 isn't calculating what was taken from your paychecks. It's calculating what should have been taken out based on the income number.

I don't know how common this is in corporate America. However, I can tell you that it is common enough I've yet to see a corrected W2 that hasn't contained this erroneous information.

A company or employer usually collects funds from your pay checks, called payroll taxes. They take that money and deposit it into their payroll tax account for the taxes due. They then report to the government what they were suppose to collect, and their statutory compulsion is over. At the end of the year, they are required to submit a W2. That W2 should report what they paid you and what they remitted in tax. However, the processes are separate in many offices and sometimes the software that creates the W2 isn't the software that determined how much tax was kept from the payments. Not all tax tables or tax software packages are created equally and money earned in different timelines is taxed at different rates, meaning overtime (pay at a higher hourly wage) is often taxed at a higher rate than your annual income justifies. Some W2s are created by manually keying the information into a document creating software package. These conditions can create a situation where your W2 reported tax remittance is less than the amount taken from your checks.

The amount you actually paid and the amount reflected on your W2 may not match. There's little chance the IRS is going to catch that you remitted more payment than the statutory reports indicate. It's possible you could remit taxes from income or paychecks that is not accurately reported, leaving unreturned overpayments.