What is the difference between an obligation and an outlay?
In U.S. federal spending, an obligation is a commitment to pay. An outlay records payment. The figures answer different questions about the same spending and should not be added together.
Following the money
An agency obligates $10 million on an award and later pays $3 million against it. The two records do not describe $13 million in purchases. One records the commitment; the other records money paid toward it.
What does a negative obligation mean?
A negative transaction can reduce a prior commitment. Check the transaction description, date and award identifier before interpreting it as cancellation of the whole program. Compare transaction changes with changes, and cumulative totals with totals.
Read the source
USAspending: analyst’s guide to federal spending data