How do I budget when my pay is partly base salary and partly bonus?

Run your day-to-day life entirely on the base salary and treat bonuses as separate, pre-assigned money. Build your monthly budget – fixed costs, savings rate, spending – so it fully works on the reliable base, which means you never depend on a bonus that could shrink or vanish. When the bonus arrives, decide its jobs in advance: a chunk to retirement or taxable investing, some to topping off the emergency fund or a goal, and a defined slice for fun. Remember bonuses are often withheld at a flat supplemental rate around 22%, which may not match your real bracket, so set aside more if you'll owe at filing. The discipline is simple: live on base, allocate bonuses on purpose. This keeps lifestyle anchored to certain income and turns variable pay into wealth.