When should you itemize instead of claiming the standard deduction

When your deduction amount exceeds the standard deduction or it lowers your income to a new bracket.

Step-by-step explanation:

When filing taxes, you are allowed to deduct specific expenses from your income. As such, it lowers your income which in turn lowers your taxes on that income. Taxes are applied by brackets. As you make more money and move up to another bracket, your percentage of your income collected as taxes is higher. When your deductions for mortgage interest, health expenses and other expenses becomes higher then the stated standard amount, you should itemize to lower your income the maximum amount. This may possibly lower your tax bracket as well.