10 The travel invoice against the approved travel request including the full per diem, along with travel allowances and preapproved other expenses, shall be automatically processed 10 days prior to departure date at the per diem rate in effect at the time of travel request approval. The actual release of the payment shall depend on the next available payment schedule. Payments are normally made by electronic transfer to the staff member's bank account and in the currency of that account. Non-US dollar payments are converted at the exchange rate prevailing at the time of payment. Non-electronic payments – in cash or cash vouchers – for staff travel are exceptional and require authorization by Treasury at Headquarters or the Budget and Finance Officer in regions.
20 Changes to per diem rates between the time of payment and travel will be automatically adjusted in the Travel Claim. However, only differences between the payment and claim amounts beyond a threshold established per office or region will result in a supplemental payment to, or a recovery from, the staff member.
30 The costs of travel by rail, bus or boat are paid in advance if a ticket has been purchased and a receipt is included with the Travel Request. Travel by private car can be paid in advance based on approved per mile or kilometre rates (see section VII.2.3). Otherwise costs are reimbursed when the Travel Claim is submitted (with receipts and other supporting documentation attached)
40 The cost of self-purchased air tickets can be included with the Travel Request, or be reimbursed after travel upon submission of the Travel Claim. In either case the receipt must be attached to the Travel Request /Travel Claim (see section VII.1.5.30-30.1-30.2)
