I logged into my TreasuryDirect account today, and what do I see?

## 28-Day Treasury Bill APY Calculator

In my previous post on Calculating and Comparing Treasury Bill Returns, it was pointed out that my APY calculation was incorrect because the way T-Bills work, you can’t actually reinvest all the interest into the next T-Bill. That is true, but what you *can* do is set your T-Bill to fund and deposit via another interest-bearing account like Capital One Consumer Bank, Emigrant Direct, or HSBC Direct. This way, you can still invest in consecutive 28-day T-Bills, and anything not rolled over to the next T-Bill is still earning decent interest.

But, we still want to compare APYs! So, what was needed was a calculator that would take all this into account. So here it is:

**28-Day T-Bill APY Calculator:**

Principal invested per $1,000 par value: **$**.

T-Bill interest earned: **$**

Bank interest earned on excess interest: **$**

**The approximate total APY is: ****%**

**Example**

Let’s do an example. Let’s take the most recent T-Bill results for a $1,000 28-day T-Bill and say you set it to reinvest every 28 days. The investment rate is 4.655%. Now, let’s say you fund via Emigrant Direct, currently at 4.50% APY. Using the APY to APR calculator^{3} and the fact that ED compounds daily, we get an APR of 4.401%.

We input these values above. It spits out that for each $1,000 T-Bill you buy, you’ll pay $996.43. Actually, you’ll pay $996.44, but that’s due to rounding errors^{2}. No big deal.

So when you buy a 28-day T-Bill, $996.44 will be taken out of your Emigrant on the next Thursday after the auction you participate in.

28 days later on another Thursday, your ED account will get a deposit of $1,000 and also a withdrawal of $996.44. $3.56 cents is left behind and earns interest at Emigrant. 28 later again, the same thing happens. Another $3.56 is left behind. This continues for a year and 13 T-Bills^{5} mature in that 364 days. At the end of this theoretical^{1} year, you’ll get approximately ($46.38 from T-Bill + $0.95 from Emigrant =) $47.33 in interest from your $996.44 initial investment. That’s an approxmiate APY of 4.75%.

It’s not perfect, but it’s something more accurate than investment rate that you can now use to compare with other online bank APYs. Note that this is pretty close to the APY that would be calculated assuming full interest reinvestment – 4.76%.

Finally, this does not take into account the tax benefits of T-Bills for those that are in states that charge state or local income taxes.

**Assumptions and Caveats**

1) The calculator assumes that the current T-Bill rate is extended out for an entire year. This cannot happen in real life as the rate is determined by auction every week. We are just extrapolating to find APY for comparison purposes. Banks change rates throughout the year as well.

2) There are plenty of round-off errors since I am allowing you to input the investment rate, which is already rounded off.

3) I again note that I am asking for the APR of the savings account you will be using, not APY. Hence, my APY to APR Calculator.

4) I am assuming that the bank interest compounds every 28 days for simplicity. Some banks compound daily, some compound monthly. It really doesn’t matter that much.

5) In actuality, there are 13.0357 (28×13= 364) T-Bills.

## Calculating and Comparing Treasury Bill Returns

Just like when teaching class, if one person asks question, usually multiple people have the same question. Unless it’s that annoying person who always ask questions like “Do I have to put my middle name on the exam? Will you mark down for that?”

Anyways, someone asked how to calculate and compare T-Bill returns to online banks, even without adjusting for tax. I’ll base this off of the recent Treasury Bill auction results. Let’s take the most recent one:

## Emergency Cash In 6-Month T-Bill Ladder

Where’s my cash? Back in December, I started forming a ladder of 6-month Treasury Bills by buying $1,000 of T-Bills at the beginning of each month. Soon, I will start reinvesting the first matured T-Bill into another 6-month T-Bill, thus having $6,000 spread out in total. So far, the strategy has worked very nicely, giving me an average equivalent taxable yield of about 5.5% (for my tax situation) in exchange for a little less liquidity. Still, I have access to $1,000 each month, and if I *really* need to, I can always use SellDirect to sell the rest at market value with a $45 fee.

I plan on ramping up to $2,000 a month, but the rest is mainly in online savings accounts because much of it is from various 0% APR balance transfer deals, and I like to be able to pay off the entire balance whenever I want. The last bit of my cash is in some longer-term CDs and I-bonds.

## Quickie: How To Buy A Treasury Bill

There seems to be some interest, so here’s a very quick example of what happens when you buy a 4-week $1,000 T-Bill.

1) Open an account at TreasuryDirect, link up checking/savings account.

2) Login, and select your amount and maturity date ($1,000)

3) You must schedule the purchase before Noon EST on the auction date (Tuesdays), otherwise you are pushed to next week.

4) Auction occurs on Tuesday, and on Thursday the discounted amount ($99x.xx) is taken out of your account.

5) 28 days later, also on a Thursday, $1000 is put back into your account if you choose so. If there is a holiday both the purchase and maturity dates are moved together. I’ll do a better example later.

## Don’t Forget About Treasury Bills To Keep Cash

People who are looking for the next best place for their cash now that ING’s Winter Sale 4.75% APY sale is over, and HSBC Direct‘s 4.80% APY promotion is soon ending, should not forget to consider Treasury Bills. You sacrifice some liquidity, but recent 28-day T-Bills have been paying 4.50-4.60% interest. Since the interest is exempt from state and local taxes, the equivalent return (calculator) can easily top 5% for those in many states. I know you can even link TreasuryDirect up with Emigrant Direct and HSBC, but I’m not sure about Capital One 360. Anyone try?

You can see my T-Bills experiences here in reverse order. Auctions for T-Bills are on Mondays and Tuesdays, so if you want in for next week you should schedule them soon.

## U.S. Treasury Bills Still Attractive Cash Option

Although I messed up my Treasury Bill Ladder by switching to 6-month T-Bills, they continue to be a pretty good cash investment alternative for those people in states with high income taxes, as they are exempt from such taxes. For example, the most recent 6-month T-Bill paid a rate of 4.754%. Using my Equivalent Rate Calculator, and a federal tax rate of 25% and state tax rate of 9%, that’s the equivalent of a regular 6-month bank CD paying **5.40%**. The 4-week T-bill equivalent rate is 5.07%.

For all my posts on Treasury Bills, please see here, reads bottom to top.

## Equivalent Interest Rate For T-Bills / Savings Bonds Calculator

I whipped out my ancient how-to-make-a-website book, and made a simple but handy JavaScript calculator for calculating the equivalent bank CD rate for a given T-Bill or Savings Bond rate, as the interest from them are exempt from local and state taxes. This uses the rate conversion formula previously given. Remember, marginal means the tax rate at which your last earned dollar is taxed. Please try it out and let me know if something’s broken:

**Calculator:**

For example, at my 25% Fed and 9% State tax rates, the current 4.14% rate for a 4-week T-Bill is the equivalent of a 1-month bank CD earning 4.70% annualized.

__Note:__ The above calculator does **not** assume that you will itemize deductions and deduct your state taxes from your federal taxes. Even if you do itemize, I would note that everyone gets the standard deduction, so it’s not necessarily fully deductible.

**Useful Resources**:

Recent T-Bill auction results

2006 Federal Tax Rates

State Income Tax Rates

## Switching to 6-Month Treasury Bills

My current 4-week T-Bill ladder has been working smoothly, with the money going in and out of the C of I so that I don’t have to do anything but watch the interest add up. But, this week’s T-Bill auction results gave a disappointing 3.63% rate, which is the post-tax equivalent of **4.13% APR** for me. I can already get that at Presidential Premier Savings.

So I think I’m going to switch to 6-month T-Bills. I chose 4-week T-Bills for their relative liquidity, as I wanted to use it as an emergency fund. But since I usually have enough cash in various accounts while earning bank bonuses, I want to grab higher yields. My savings horizons are longer than 6-months too. The recent 6-month T-Bill rates are about 4.33%, or **4.92% APR** bank equivalent for me. That’s much higher than any 6-month bank CD. I think I may be getting too obsessed with optimizing my cash returns, but it only takes a few clicks =)

## 4-Week T-Bill Ladder Complete

I now have 4 consecutive 4-week Treasury Bills as a ladder, so next week one will mature and I will buy another 4-week T-Bill the same day with the proceeds. I’ll keep this rotating money as my emergency fund until the rates are non-competitive. For now, I’m averaging the equivalent of a 4.5% bank APY with only slightly less liquidity.

(For the history on me building this T-Bill ladder, please read the entries in my Treasury Bills Category)

## Buying T-Bills: Can’t Back Out After Rate Announcement

One bad thing about purchasing Treasury Bills at TreasuryDirect is that you don’t know the exact return of the T-Bill before you buy it. An interesting idea around this was presented by commenter Dan when I first posted about buying T-Bills:

You don’t have to commit until you know the price. 1. Schedule the transaction. 2. The auction will be on Monday for 3- or 6- month T-bills and Tuesday for 1-month T-Bills. 3. On Wednesday, look at your pending transactions. … At the bottom of the page, you have two button options. … “Delete” (which I assume means cancel the transaction, though I haven’t done it myself).

## How Treasury Bill Auctions Work

Reader Dan pointed out an interesting (well, kind of) research article [pdf] that, amongst other things, explains how Treasury auctions work. As stated on the Treasury Direct site, you can buy T-Bills through either a competitive or non-competitive bid. On the surface, it would seem that you would want to put in a competitive bid to get the best price. But it’s a little fuzzier than that. If you put in a noncompetitive bid, you are just about guaranteed a bill to buy. Everyone else put in a bid for what they are *willing* to pay, but may not get it.

After reading the article, I put together a little example on how the bidding process works. As usual, please point out my blunders.

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