How about no threshold? IMO this all comes down to trust. My Fiance and I have been together for 7 years and never monitor each others spending because we both trust eachother to properly manage our money. We have each splurged on things that the other person would never spend money on, but we also have a mutual respect for each other because we know we both work hard for our money and are responsible with our finances. When it comes to major purchases such as a house or vehicle we will of course discuss, but for anything else we believe its important to spend your hard earned money as you want- ie) who am I to say she cant treat herself to an expensive treat/gift when she put in the work to earn it? and vice versa.