Changes to a project budget affecting the outputs, completion date or total estimated project costs require a formal budget revision that is agreed by the signatories of the original project document, and may need the approval of the donor, UN pooled fund steering committee or vertical fund, if relevant. The UNDP programme manager alone may sign the revision provided the other signatories have no objection. This procedure may be applied, for example, when the purpose of the revision is only to re-phase activities among years.