How I would (and might) maximize the current Series I Savings Bond deal

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There’s an interesting deal available right now for folks who have extra cash lying around they are sure they won’t need for a least one year, and ideally won’t need for five.

Fixed-rate inflation-adjusted Series I Savings Bonds

When I first learned about this deal at Doctor of Credit I admit I scoffed. The high interest rate he described is on an annualized basis, but you’re only guaranteed the reported rate for 6 months, meaning you don’t even get a full year at that rate; it could drop to 0% for the second half of the year before you’re eligible to redeem your bonds, meaning you froze up to $10,000 in cash in a security earning nothing for 6 months of the year!

But, the more I thought about the deal, the more I came to appreciate the potential possibilities. So let’s take a closer look.

Series I Savings Bonds have 4 curious features:

  • When issued, they have a fixed rate of interest that is known at the time of issuance and lasts for 30 years or until the bond is redeemed;

  • added to that fixed rate is a variable, inflation-adjusted rate of interest that is calculated in November and May of each year and applied to outstanding bonds every 6 months (so a bond purchased in January has November’s rate until July — this will become relevant shortly);

  • bonds earn interest starting from the first day of the month they’re purchased, so bonds purchased November 30 will earn interest from November 1;

  • with limited exceptions, they must be held for 1 year, and redemptions are penalty-free after 5 years (you sacrifice 3 months of interest if redeemed between 1 and 5 years after purchase. I’m genuinely unsure whether the 1-year holding requirement is to the calendar date or to the calendar month of purchase — if you know, leave a comment!)

Finally, you’re limited to $10,000 in purchases through Treasury Direct per calendar year. You can purchase an additional $5,000 in I bonds through your tax refund, although which fixed and inflation-adjusted rate you get will depend on when Treasury transmits the order to the “Treasury Retail Securities Site in Minneapolis,” so you may not be able to get November’s rates if you file for an extension or your refund is delayed for any reason.

Why do I keep talking about November’s rates?

The fixed rate on Series I Savings Bonds, the minimum rate you’re guaranteed to earn for 30 years, is 0% APY, and has been for most of the last decade. But due to the method Treasury uses to calculate the inflation component of the interest rate, bonds purchased from November 1, 2021 through April 30, 2022, will earn a guaranteed interest rate of 7.12% APY.

Now be careful to understand what’s happening here: APY is calculated on an annualized (that’s the “A”) basis, but you’re only guaranteed to earn that rate for the first 6 months you own the bond. After 6 months, the inflation-adjustment will change to May’s rate, and 6 months after that (when the bond is eligible for redemption with a 3-month interest penalty) it will change to the November, 2022, rate.

Series I Savings Bonds are a highly optioned contingent bet on future inflation rates

One way of assessing a bond investment is to look at its “yield-to-worst,” which refers to the yield you would receive if, for example, a corporation or utility exercised a call option at its face value on a bond to refinance its debt at a lower interest rate before the end of the bond’s term. For a fixed-rate, zero-risk, United States Treasury bond, the yield-to-worst is simply the yield on the bond.

The inflation-adjusted interest rate and possibility of early redemption essentially means Series I bondholders are making a bet on the future of inflation rates, but one in which they have all the power.

You may believe, as I do, that May, 2022’s inflation adjustment will be sharply lower than November, 2021’s. So, what’s the yield-to-worst? Since the inflation adjustment is never less than 0%, and the fixed-rate is 0%, you would earn 0% in interest during the second 6-month holding period. In that case, your yield would be 3.56%. That’s not a shoot-the-lights-out great investment, but it’s a solid return on a completely safe investment. After 12 months, you can pull the money out (sacrificing 3 months of 0% interest) and do something else with it.

But however much you think inflation (technically the CPI-U measure of inflation) will fall between now and May, 2022, it probably won’t fall to 0%. Say it falls to 1.9%, which was fairly common prior to the pandemic — now you’ve earned 4.035% on your investment (after sacrificing the last 3 months of interest), which suddenly starts to look pretty comparable to the rewards checking accounts I regularly write about and use.

Optionality is very valuable

When you take this exercise a bit further, you can see the possibilities are even more lucrative than I’ve suggested, since after one year, you always have three options: “letting it ride,” “trading up,” or “cashing out.”

Every November and May, when the fixed rate and inflation adjustment are announced, you can see what the composite rate will be for the next 6 months:

  • Let it ride: if the inflation adjustment remains higher than your other investment opportunities, you can leave the money to earn for another 6 months until the next adjustment, bringing you 6 months closer to the 5-year penalty-free redemption threshold;

  • Trade up: if fixed interest rates soar and inflation crashes, then you can redeem your current 0% fixed-rate bonds and buy new, higher fixed-rate bonds;

  • Cashing out: if fixed interest rates stay low and the inflation adjustment crashes, you can redeem your bonds and do anything you like with the money.

Obviously this is just another way of saying money is fungible and Series I bonds can be redeemed after one year. What makes this interesting is that this series of options continues every 6 months for 30 years!

What’s the optimal strategy to maximize optionality?

Due to the $10,000 Treasury Direct and $5,000 tax refund purchase limits, I believe the optimal strategy looks something like this:

  • buy $10,000 in bonds by December 31, 2021 through Treasury Direct;

  • in April, 2022, when the March CPI-U data is announced and the May, 2022, inflation adjustment is finalized, you’ll know the total annualized interest rate you’ll earn (6 months at November’s rate, and 6 months at May’s rate), and can decide whether to purchase another $10,000 through Treasury Direct based on that composite annualized rate;

  • finally, by April 15, 2022, decide whether to lock in an additional $5,000 in bonds at the November/May composite rate, or file a tax extension and wait until October, when the November 2022 rate will be finalized, and decide then.

Obviously this represents a lot of corner cases and attention to detail, so it’s not for everyone. November’s rate is so high it would be perfectly rational to just lock it in with $10,000 this year and next year through Treasury Direct, and $5,000 next year through a tax refund. But since the genius of these bonds is their optionality, this is one way you can maximize that value.