"ATM" stands for "automated teller machine" which is a computer controlled terminal which allows customers to make deposits, make cash withdrawals, check bank balances, and other financial transactions.
The phrase "mortgage interest expense" refers to interest paid on a mortgage loan that is fully deductible up to certain limits when the taxpayer itemizes deductions on his or her tax return. For more information, see "Home Mortgage Interest" in IRS Publication 17, Your Federal Income Tax, available at www.irs.gov.