Zero-Based Budgeting (ZBB) is a process where every ministry must justify its entire budget request from scratch (zero base) every year, rather than simply adjusting the previous year's budget for inflation.

Unlike incremental budgeting, which assumes past expenditures are necessary, ZBB requires a rigorous cost-benefit analysis of all proposed programs, regardless of their historical funding. While theoretically highly efficient for eliminating wasteful, obsolete schemes, it is extremely resource-intensive and time-consuming, which is why it is rarely implemented in its purest form across entire national governments.