If I have a rental property in the U.S., what do I need to attach with my US tax returns to ensure the IRS accepts the figures reported?

When submitting your tax return to the IRS, you must ensure that all figures that you claim as an expense have the proper documentation submitted with them. Additionally the receipts and invoices you submit along with your tax return must prove:

1. The expense is reasonably considered to be an ordinary expense given the nature of the business.
2. The expense was actually incurred in the tax year, and
3. The expense was paid for.

Please note, for the most notable expenses for rental properties such as property taxes and mortgage interest, your bank will issue a 1098 to corroborate these figures.