Cubby needs help!

I need some help and suggestions from any of you animal lovers... Cubby has taken to marking everything within minutes of being in the house and it is driving us nuts! So far we have gotten lucky and he has only gotten my bags but he got Jeff's workout bag and boy was Jeff ticked off this morning. So Cubby has now lost all privileges of coming indoors. He is getting neutered in August and that is suppose to help, I am worried about winter coming and him needing to come in a lot more. Any suggestions?