While the amounts you show are correct – and are the total amount of interest that I bond had earned up to that date – the rates you show for those months aren’t correct.

In Jan 06 this I bond earned 4.70%. In Jan 07 it earned 2.11%. That’s what accounts for the 2006 interest being twice as much as the 2007 interest.

I think you may misunderstand how I bond interest rates are determined.

Tom Adams

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$10,000 I Bond purchase Aug 2003

Earnings rate is 4.52% (Nov06)

Feb 07 calculated interest earned is $1412

Jan 07 calculated interest earned is $1392

Interest increased by $20 between Jan & Feb (1412-1392)

Same $10,000 I Bond purchase Aug 2003

Earnings rate is 4.12% (Nov05)

Feb 06 calculated interest earned is $848

Jan 06 calculated interest earned is $808

Interest increased by $40 from between Jan & Feb (848-808)