When you apply for a loan on commercial property, the loan is based on the income level you provide. The loan amount is based on current income and projected income. When Trump would seeks a loan on one of his skyscrapers, the bank would ask for financial documents and use them to determine the loan amount.
A commercial building is taxed differently than your residence. When taxing a large office building, you furnish financials showing the rent, occupancy rate, and profit. The value is determined by analyzing market rent and typical expenses and applying a market capitalization rate. This approach provides a value based on net operating income.
The problem was he maintained 2 sets of books and showed the loan officer a higher profit and the tax authority a lower one. Trump signed off that the numbers provided were correct. Due diligence is based on the numbers you provide. Folks, that’s called fraud.