What is Interest Previously Reported on a Treasury Bond?
If you already reported the interest from the bond's value increasing each year on previous tax returns, you won't be taxed on that interest again. The amount of previously reported treasury bond interest you enter will decrease the amount that is taxable on this year's tax return.
For example, if you receive a Form 1099-INT with $100 in interest income, but you've already reported $70 of that interest as income in previous years, then only $30 should be reported as taxable income this year.