Have you not been reporting bank interest income?
Note that your bank is required to issue a 1099-INT if they pay more than $5 of interest, and the IRS gets a copy, which your mortgage broker may review. If you have failed to claim interest, the IRS should be sending you a bill for income tax due. If you try to claim more interest than you actually earned on your mortgage application, that may show up when the underwriter reviews your past tax returns.
