Picture a city at the end of its fiscal year. Property tax payments from residents are still trickling in, sales tax remittances from local shops haven’t been collected yet, and a state grant for a new park arrived in the mail two days ago. When can the city actually count these as “revenue” in its books? In businesses, revenue usually shows up when the sale happens. For governments, the answer depends on a quirky rule: money must be measurable and available to pay this year’s bills. This chapter unpacks that rule—the modified accrual basis—and shows how it turns common government income like taxes and grants into recognized revenue.