It is very important to understand the rules for claiming travel expenses when your trip combines both business and a holiday.
Airfares: If the predominant reason for the trip is business, and some portion of the trip is also a holiday, then your total airfare would be deductible. This is likely to be the case for when you go to a conference and you stayed over for some additional time. You could prove the reason for the trip was the conference. However, the airfare for your spouse would not be tax deductible.
Accommodation: Where your spouse accompanies you, their portion of accommodation expenses cannot be claimed. Nor can you claim the portion of accommodation expenses for the time you are on holiday.
Documentary evidence must be maintained and the rules are different for domestic and international travel.
We suggest that if you are considering a trip with dual purposes, you should call Saward Dawson just to check what you need to know in advance.