Up to you but it will only be used to negotiate against you. If they like you they can offer what they will. In 40+ years at various jobs I've never submitted or even been asked for this, but I suppose in some cultures it may be "normal". Personally it's none of their business IMHO, and their asking for it is a red flag to me. I would politely say " I am not comfortable sharing this information with you, thanks anyway. "

Ask your employer if they offer a non qual plan. It's a form of deferred compensation that doesn't qualify for the 401k tax code and can be used in addition to traditional 401k. A non qual can reduce your immediate tax liability and even grow through investment choices. It's usually only available to corporate officers, executives, or other highly compensated employees, and not all companies offer it. Consult a tax or investment advisor before enrolling as there are different forms of non qual plans and some carry significant risk should your employer become insolvent.