If they can show you a search order then they can, if not then just tell them you are agreeing to let them in unless they have a court order. This will become ugly though as they will come back with a court order and possibly with police escort to enforce the order. If you are not hiding anything, you can let them in. CRA entering your home, for what - if possibly your business is a home based business and they doubt whether it exists or not. Or if your business transaction does not fit your tax filing and your residence is where you do your business, they would want to see inside for sure.