Is it permissible to submit an unrealistic budget to banks with Islamic branches in order to obtain banking facilities, given that the bank’s rights are secured by a real estate mortgage whose value is greater than the facilities?

Lying or cheating is not part of a Muslim's ethics. One must avoid submitting an unaudited budget to the bank, as that is considered cheating. Rather, an audited budget must be submitted, or the bank should be approached to be excused. Providing collateral to the bank is not sufficient, as they have specific purposes for requiring an audited budget.