Well-organized records will make it easier to prepare your tax return and will help you answer questions if your return is selected for examination, or prepare any response if you are billed for additional tax.
Records such as receipts, canceled checks, and other documents that support an item of income or a deduction appearing on your return should be kept until the statute of limitations expires for that return. For assessment of tax you owe, this generally is 3 years from the date you filed the return. For filing a claim for credit or refund, this generally is 3 years from the date the original return was filed, or 2 years from the date the tax was paid, whichever is later. Returns filed before the due date are treated as filed on the due date. There is no statute of limitations when a return is fraudulent or when no return is filed.
If you are an employer, you must keep all your employment tax records for at least 4 years after the tax becomes due or is paid, whichever is later.
If you are in business, there is no particular method of bookkeeping you must use. However, you must use a method that clearly and accurately reflects your gross income and expenses. The records should substantiate both your income and expenses. Publication 583, Starting a Business and Keeping Records (PDF), and Publication 463, Travel, Entertainment, Gift, and Car Expenses (PDF), provide additional information on required documentation for taxpayers with business expenses.