An executive authority shall enter into a collective agreement in the appropriate bargaining council on any matter that has financial implications only if—
||he or she has a realistic calculation of the costs involved in both the current and the subsequent fiscal year;
||the agreement does not conflict with the Treasury Regulations; and
||he or she can cover the cost—
||from his or her departmental budget;
||on the basis of a written commitment from the Treasury to provide additional funds; or
||from the budgets of other departments or agencies with their written agreement and Treasury approval.