For conceptual challenges try Palestine where there are two budgets:
1. the recurrent budget which is funded through domestic revenues and general budget support; this basically funds a few transfers and civil service salaries/goods and services; and
2. the development budget which is not really a budget, but rather the sum of all donor project support; this pays for the vast majority of policy reforms and public investments. Of course, no one really knows how much funding comes from donors since this would require full compliance to the reporting rules by every donor as very little flows through the government system.
Accordingly, when Palestine prepares a national development plan, as it is at the moment, the funding for implementing the plan's priorities, other than the related civil service salary costs, will all come from donor contributions (i.e., the development budget). Unfortunately, the past or future total of the development budget is unknown and remains subject to the usual delays, uncertainty, pledge/disbursement gaps, and other vagaries of competing donor processes.
And did I mention that large portions of the domestic revenue rely on prompt, fair, accurate transfers of "clearances" from the Israeli authorities. Now try applying the famous three levels of the World Bank Handbook to that, and pity the MoF Budget Director who is asked to do so.