From Wikipedia

Connection between budget and proposal

The budget should be absolutely in line with the proposal. The best way to prepare the budget is to read the Methods section in detail while identifying all cost drivers. For example, if one of the aims of the Methods section states that data will be prospectively collected, then the corresponding budget should include a research coordinator, software for data collection and data management, etc. Reviewers will keep checking the budget as they read the proposal, and so a strict connection between budget and proposal is absolutely essential

Budget values

Budget values should be reasonable, within market values, and based on common sense. They are reasonable and within market value if they agree with general market value for the task being charged. Budgets with round numbers are usually a sign that no thought was given or research was performed to find real costs -- for example, saying that a computer will cost $3,000 dollars is a sign that the person preparing the budget did not really do a good job. Last, common sense should prevail -- for example, if one task is obviously more expensive than another, prices states in the budget should comply with that rule.

SOP's

• Alignment with proposal text

The proposal should be read multiple times to identify cost drivers that need to be factored in the budget. Adequate explanation to each cost driver should be provided in the budget justification. Personnel effort should be based on the actual tasks outlined in the proposal. Assumptions should have a proper justification/rationale

• Broken numbers

The use of whole numbers for each cost driver should be avoided. Wherever possible Breakup for the amount should be furnished

• Common mistakes

Absence of cost driver in proposal and vice versa Over or under costing Miscalculating personnel effort