You must keep records as long as they may be needed for the administration of any provision of the Internal Revenue Code. Generally, this means you must keep records that support your deduction (or an item of income) for 3 years from the date you file the income tax return on which the deduction is claimed. A return filed early is considered filed on the due date. For a more complete explanation of how long to keep records, get Publication 583, Starting a Business and Keeping Records.
Reimbursed for expenses. Employees who give their records and documentation to their employers and are reimbursed for their expenses generally do not have to keep copies of this information. However, you may have to prove your expenses if any of the following conditions apply.
You claim deductions for expenses that are more than reimbursements.
Your expenses are reimbursed under a nonaccountable plan.
Your employer does not use adequate accounting procedures to verify expense accounts.
You are related to your employer as defined under Standard Meal Allowance in chapter 1.
Reimbursements, adequate accounting, and nonaccountable plans are discussed in chapter 6.
Information courtesy of the Internal Revenue Service.