Hi, it is important to keep your OBC certificate updated every year. Because if any authority asks you for you OBC Certificate, they'll ask you for your annual income certificate as well. Here you have to provide either your annual income details if you're working and if not then your parents' annual income details. You must be aware of the creamy and non creamy layer in OBC Category itself. So that depends on the annual income. 

Any hike in the income crossing the annual salary limit will be considered under creamy layer and if it's under that limit then you'll be considered under non-creamy layer. Hence, it's important.