They are important for bookkeeping because they keep clear records of your purchases and expenditures, which helps you comply with IRS rules. Correctly documenting your receipts for all your transactions can help your business maximize its possible tax reductions. Ensure to save receipts for items you will deduct from your income when it's time to file your taxes. If the IRS conducts an audit on your business, you can show that the amount you deducted came from allowable expenses.