According to this section, the following expenses may be deducted if the missionaries are "away from home":

- reasonable expenditures for meals
- lodging necessarily incurred while away from home in the course of performing donated services
- out of pocket transportation expenses.


In order to be "away from home" the missionaries must retain their former home. The deduction for personal living expenses (meals & lodging) is premised on the idea that while "away from home" they have duplicated expenses. (or that meals are burdensomely more expensive when "away from home.") If they sell their home before they go or rent it out at fair market rates they don't have a home to be "away from", so they wouldn't be able to deduct meals and lodging.

My firm has been following these guidelines for years and we have never had any issues.