U.S. taxpayers: Yes—if the trip to Mexico is undertaken primarily for business (e.g., scouting real‑estate opportunities), the airfare, lodging, meals (subject to the 50 % limit), and other ordinary and necessary expenses are generally deductible under IRC 162. The travel must be “away from your tax home” for a period substantially longer than a normal workday, and you must keep detailed records showing the business purpose and allocating any personal days. Because the travel is abroad, you must allocate expenses between business and personal portions (e.g., days spent on site versus leisure) and retain receipts; the IRS also applies the “foreign travel” rules that limit deductions for meals and lodging to the same limits as domestic travel.

Norwegian taxpayers: Business‑related travel expenses can be deducted when they are not reimbursed by the employer and are properly documented (tickets, receipts, etc.). The Norwegian Tax Administration allows a deduction for travel between home and the permanent place of work, calculated at a fixed rate, and also permits claiming actual expenses for work‑related travel—including abroad—provided they are substantiated . If the employer pays for the travel, the employee cannot claim a separate deduction . Thus, a Norwegian investor who personally funds a fact‑finding trip to Mexico and keeps supporting documents may deduct the airfare, accommodation, and reasonable meal costs as business expenses.

Bottom line: Both U.S. and Norwegian investors can write off a business‑purpose trip to Mexico, but they must meet the respective documentation, allocation, and non‑reimbursement requirements to substantiate the deduction.