What is the central premise of Kant's Categorical Imperative?

The central premise of Kant's Categorical Imperative is that moral actions should be guided by universalizable principles, meaning that you should only act according to a maxim – a rule or principle – that you could at the same time will to become a universal law. This means that a moral rule should apply to everyone, everywhere, without exception. The Categorical Imperative, according to Immanuel Kant, is a command of reason that is not dependent on any particular desire or outcome, setting it apart from hypothetical imperatives, which depend on what you want to achieve. A key element is treating humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end. This requires respecting the intrinsic value and dignity of every individual. For example, if you are considering borrowing money with a promise to repay it, knowing you cannot, you must ask yourself if lying to get money could become a universal law. If everyone lied to get money, the very concept of promising would collapse. Therefore, because you could not rationally will such a maxim to become a universal law, lying in this situation is morally wrong according to Kant's Categorical Imperative.