The noun budget is one that is used by nearly every individual and corporation on a daily basis. It can be defined, generally, as a particular sum of money that has been allocated for a particular item, purpose, or event over a specific or fixed period of time. An example of the term “budget” defined in this sense would be “Our monthly budget for entertainment has gone from $200 to $500 following my recent raise.” It can also refer to the itemization of anticipated expenses during that given time period along with, in many cases, proposed methods of financing those expenses. An example of this usage could be “I began preparing a budget for the end-of-year party.” In terms of project management, the work budget has similar meaning. A budget represents an approved estimate for either the entire project or for a particular schedule activity or work structure breakdown component. Budgets can be modified with proper approval at any point throughout the process, however, it is typically ideal to adhere to the predetermined budget whenever possible.
This term is defined in the 3rd and the 4th edition of the PMBOK.
Under what conditions would a project manager make changes to a baseline without any impact to project budget?
When would a project manager not allow changes to a baseline?
Changes to a baseline could be possible if the project manager makes use of Fast Tracking, provided this method has no impact on the budget (which should not be the case).
Whether a project manager is allowed to make changes to a baseline or not depends on the authority the project manager is given, e.g. with respect to shifting a budget.