You are under no obligation that I know of. Had a similiar situation - well kinda. I prepared the return and took the credit (long time homeowner) with the understanding that the taxpayer was going to occupy the home due to a relocation. Following year the taxpayer shows up and still has the same OLD address and I inquire and she says, "oh, our daughter is living there, that's OK right?" I explained the facts with the statement that if they wanted to continue utilizing my services they needed to do the right thing. I sent them home to comtemplate it and to their credit, they called back within the hour and said they were coming back to fix things - and they did. Your guy? Good luck. But I seriously doubt that you will hear from him again. But if you do, stand your ground - it is the right way, or the highway!