Usually, the answer is yes.

It is the policy of most major businesses and corporations to allow spouses on business trips, as long as their is no additional expense incurred to the company. The guest must be responsible for their own meals, snacks, entertainment,airfare etc. However, it is usually acceptable for spouses to share a hotel room, provided that it does not account for any additional costs. Likewise, car rental costs can also be deducted, since it won't cost any more for a spouse to come along.

It is acceptable for spouses to go along on business trips provided that they will not hinder the productivity. It should be expected that the spouse will not attend any private business functions where their presence could be a problem. For the most part, as long as the spouse will be a help and not an issue, it should be allowed.

Make sure that employees know which expenses will be deducted and which will have to be kept separate.

Allowing spouses on business trips is a great way to allow your employees to incorporate some family time into their work time. Everyone likes a nice and understanding boss, and this is one way to connect with your employees. These days, family time is very important, so any additional time your employees can use to connect with their loved ones will be greatly appreciated. As long as your employees can handle that, there should be no issue with allowing spouses on business trips!