Deposit Security Act This bill increases the amount of deposit insurance available to noninterest-bearing transaction accounts through the Federal Deposit Insurance Corporation (FDIC) and the National Credit Union Administration (NCUA). Under current law, deposits are generally insured up to $250,000. Specifically, noninterest-bearing transaction accounts at FDIC-insured depository institutions and at NCUA-insured credit unions must be insured up to $10 million. However, an institution or credit union may opt-out of this insurance during the 30-day period beginning on the date the program starts. In addition, the maximum deposit insurance amount must be adjusted for inflation every two years.