To prove travel expenses for taxes, you should keep a record of your expenses, such as receipts, vouchers, and invoices. As a general rule of thumb, don't write off an expense unless you can prove it relates to work.
If you choose to claim an expense without a receipt, make sure you have other proof of the transaction, either on a bank statement or as detailed notes. You need to be able to demonstrate that the expense is solely for business use and that the amounts have been recorded and calculated accurately.
Whether you lost your receipts, they were damaged, or you simply don't have them, there are several documents you could use as evidence to answer an IRS audit when you have no receipts: Calendar logs of meetings/travel/daily tasks. Canceled checks. Credit/debit card statements.
You should keep adequate records to prove your expenses or have sufficient evidence that will support your own statement. You generally must have documentary evidence, such as receipts, canceled checks, or bills, to support your expenses.
A taxpayer is traveling away from home if they are away for longer than an ordinary day's work and they need to sleep to meet the demands of their work while away. Travel expenses must be ordinary and necessary. They can't be lavish, extravagant or for personal purposes.
How do I ask for reimbursement of travel expenses? Politely approach your supervisor with an itemized list of expenses incurred or expected during the travel and offer a clear reason why this travel is critical to your work and the responsibility of the company.