The Zero-Percent Certificate of Indebtedness (C of I) is a Treasury security that earns no interest. That might sound like a bad deal at first glance, but that’s not really the point of it — it functions as a sort of holding account within TreasuryDirect, a place to park cash until you’re ready to buy actual interest-bearing Treasury securities. There’s no limit on how much you can keep in one.
On March 1st, 2026, TreasuryDirect is removing the ability to set a C of I as a payment destination, and you won’t be able to send money directly from your bank into a C of I through BuyDirect anymore either.
That said, if you already have a C of I set as your payment destination before that date, nothing about your existing setup gets disrupted. Redemptions and payments will keep flowing into it as usual. You’ll also still be able to spend whatever balance you have — either to buy securities or redeem it back to your bank. The TreasuryDirect FAQ has more detail on how this transition works.
When you go through BuyDirect to make a purchase, select “Zero-Percent C of I” under Source of Funds. One thing worth knowing: electronic deposits that arrive on a given day get credited to your C of I just before any securities are issued that day. So if your deposit has cleared by your purchase request date and your balance covers the amount, the security gets issued on time with nothing else required from you.
On any day funds are pulled from your C of I, transactions go through in this order:
If your balance doesn’t cover everything scheduled for that day, the transactions that can’t be funded will be canceled automatically. It’s worth checking your balance periodically if you have purchases lined up.
If a payment to your bank account bounces back for any reason, those funds get deposited back into your C of I automatically. From there, you decide what to do — buy securities with it or redeem it out to your bank.
You can pull money out of your C of I at any time, in any amount. It transfers straight to your linked bank account.
Every transaction connected to your C of I — purchases and redemptions alike — shows up in your C of I History, so you have a running record of everything in one place.