HRA reimbursements are taxable if they are more than the medical expense (excess reimbursement). HRA reimbursements would also be taxable if you paid the expense last year, took a tax deduction, and then got reimbursed this year, because it would be a reimbursement of a previous deduction. HRA reimbursements would also be taxable if you used an HSA to pay the same expense, since that would be double dipping.
But most of the time, HRA reimbursements are not taxable and you will not get any tax paperwork from the plan.