With the release of the March 2013 CPI-U figures ^{[3]}, we now know the variable interest rate on Series I Savings Bonds for the next six months starting in May and it continues to be low (but it’s an increase from the last six months – so that’s good right?).

The March 2013 CPI-U figure was 232.773 and the September 2012 CPI-U figure was 231.407 so we can calculate a semi-annual increase of 0.590% and we’d expect the variable component of the bond to be 1.18%. The only question is whether there will be any change in the fixed rate, which currently sits at 0.0%. With interest rates so low, no one expects that to change anytime soon.

That said, using the equation:

Bond rate = Fixed rate + 2 x Semiannual inflation rate + (Semiannual inflation rate X Fixed rate)

Bond rate = 0 + 2 x 0.0059 + (0.0059 X 0)

Bond rate = 0.0118

So we’d expect the interest rate on Series I Savings bonds to be 1.18% in May.