Large discrepancy between last year and this year

When it comes tax time, there are several ways to find yourself getting a smaller refund or even owing the IRS or your State money.

• You may not have had enough withholding from your paycheck or your deductions may have changed, resulting in a lower refund or the need to pay additional taxes with your return.  If you claim too many allowances, you won't have enough withheld to cover your tax obligation. The W-4 comes with instructions on how to treat various allowance options.
• Did you take an additional job or did your spouse start working? Again, if you didn’t adjust withholding, you may come up short at tax time.  If you both work and both claim spouse deductions, you likely won't have enough deducted.
• If you were previously eligible for the Earned Income Credit (EITC) and your income increased, your EITC may be reduced or eliminated entirely. Since the EITC is a direct deduction from your tax liability, the elimination of the deduction will increase what you owe.
• Did you start a business? Maybe Airbnb or Uber?  You must report self-employment income to the IRS. In fact, any company that pays you $600 or more during the year must send you a 1099 form recognizing the non-employee compensation. If you don't have extra money withheld through your regular work paycheck, you would likely owe when it is time to file your taxes. To avoid owing additional tax and any penalties, you should pay estimated taxes on your self-employment income quarterly.
• Did you have a good year in the stock market? You owe a percentage of your good fortune to the IRS. Typically, financial services companies and brokers don't withhold money from investment gains.
•  Other money that may be subject to income tax includes:
• Gambling winnings
• Unemployment
• Prizes
•  More reasons for increased taxes:
• Change in filing status
• Gain or loss of child tax credit eligibility
• Change in education or tuition deduction
• Change in home or property tax
• Change in military service

None of these apply to me. How can I talk to someone who can see my account?