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

Complete
United Kingdom → Tehran, IR
Item Name Destination Amount Conditions
Meals Tehran, Iran 559938.5 IRR per day Over 5 hours rate: covers subsistence expenses for a period of more than 5 but less than 10 hours, measured by reference to the times of arrival in and departure from the foreign country.
Meals Tehran, Iran 1313334.5 IRR per day Over 10 hours rate: covers subsistence expenses for a period of more than 10 but less than 24 hours, measured by reference to the times of arrival in and departure from the foreign country.
Meals and incidentals Tehran, Iran 1509517.5 IRR per day 24 hour rate: covers the total cost of meals and daily hotel-to-office travel for a full 24-hour period.; The actual room rate is paid in addition to this amount (source shows the rate as 'plus room rate').
Lodging Tehran, Iran 139 USD per night No specific conditions
Breakfast Tehran, Iran 0 IRR per meal This amount is included in the room rate, so it is not paid separately on top of the lodging rate.
Lunch Tehran, Iran 498631 IRR per meal No specific conditions
Dinner Tehran, Iran 692089 IRR per meal No specific conditions
Incidentals Tehran, Iran 0 IRR per day Source row labelled 'Other': other expenses incurred during the day; employers may use the individual meal and other rates instead of the over 5 hour, over 10 hour and 24 hour rates.
Drinks Tehran, Iran 122614.5 IRR per day No specific conditions
Transport Tehran, Iran 196183 IRR per day Covers daily travel between the employee's hotel and office.
Total residual Tehran, Iran 1509517.5 IRR per day Total residual rate: intended to cover the total cost of meals in a period of 24 hours plus the cost of daily travel between the employee’s hotel and office; the 24 hour rate is the sum of the room rate and this total residual rate.

Source URL:
https://www.gov.uk/guidance/expenses-rates-for-employees-travelling-outside-the-uk
This source provides official travel rate information from gov.uk.