Look up per diem reimbursement rates and mileage deductions for business travel worldwide.

Complete
Ireland → Vietnam
Item Name Destination Amount Conditions
Meal & Lodging Hanoi, Vietnam 240 USD per night Overnight rate covering accommodation and three meals for a 24-hour absence abroad on official business.
Vouched Accommodation (VA) Rate Hanoi, Vietnam 120 USD per night Vouched Accommodation (VA) rate: paid in addition to the vouched cost of accommodation. Per Note 2 of Circular 07/2017 the VA rate should not be routinely used except for travel to Brussels, where the vouched cost of room plus the VA rate applies to all officers on overnight visits.
Daily allowance Hanoi, Vietnam 80 USD per day Ten-hour rate: applies to an absence abroad of ten hours or more without an overnight stay.
Daily allowance Hanoi, Vietnam 40 USD per day Five-hour rate: applies to an absence abroad of between five and ten hours.
Meal & Lodging Ho Chi Minh City, Vietnam 231 USD per night Overnight rate covering accommodation and three meals for a 24-hour absence abroad on official business.
Vouched Accommodation (VA) Rate Ho Chi Minh City, Vietnam 115.5 USD per night Vouched Accommodation (VA) rate: paid in addition to the vouched cost of accommodation. Per Note 2 of Circular 07/2017 the VA rate should not be routinely used except for travel to Brussels, where the vouched cost of room plus the VA rate applies to all officers on overnight visits.
Daily allowance Ho Chi Minh City, Vietnam 77 USD per day Ten-hour rate: applies to an absence abroad of ten hours or more without an overnight stay.
Daily allowance Ho Chi Minh City, Vietnam 38.5 USD per day Five-hour rate: applies to an absence abroad of between five and ten hours.
Incidentals All Other, Vietnam 10 EUR per day Actual-cost destination (Note 1, Circular 07/2017): the overnight rate is the vouched cost of accommodation and three meals, the ten-hour rate is the vouched cost of two meals and the five-hour rate is the vouched cost of one meal, in each case plus this incidental expenses allowance of EUR 10 per day.; Applies to locations in Vietnam other than those separately listed in Appendix 2 of Circular 07/2017.

Source URL:
https://www.revenue.ie/en/employing-people/documents/dper-circular-07-2017-subsistence-allowances-abroad.pdf
This source provides official travel rate information from revenue.ie.