How should I handle an unexpected expense that wasn't in my budget?

First, decide whether it's a true emergency – urgent, necessary, and unexpected – or just an unplanned want. A real emergency is exactly what your emergency fund exists for, so use it without guilt and then prioritize refilling it over the next few months. If you don't yet have a cushion, cover the cost from your most flexible category and pause discretionary spending until it's handled, rather than reaching for a credit card you can't pay off. For costs that are unexpected but not urgent, give yourself time to plan and fund them from a sinking fund instead. Afterward, ask whether the 'surprise' was actually predictable – many are – and create a sinking fund so the next one isn't a shock. Replenishing the safety net is the first priority once the bill is paid.