"Self-repaying loan" is an appealing phrase, and appealing phrases invite people to fill in the gaps with things that are not true. This post is the list of things Corpus does not do. Some of them are limits of this implementation; most are limits of the idea itself.
Start with the one that overrides the rest: today the yield is zero, because every market routes collateral into a 1:1 custody vault and no earning vault for these tokens exists on this chain. Nothing below is currently happening at all. Everything below describes the mechanism as it will behave when there is something to harvest.
It cannot protect you from a falling price
This is the big one, and nothing in the design touches it.
Self-repayment reduces your debt gradually. Liquidation is triggered by your collateral's value falling quickly. Those operate on completely different timescales. A yield stream that retires a few percent of your debt a year is irrelevant to a name that drops 20% in a fortnight.
Your health factor is collateralValue x liquidationThreshold / debt. Self-repayment nudges the denominator, slowly. The market moves the numerator, at whatever speed it likes. Corpus is an ordinary collateralised loan with an unusual repayment source, and ordinary collateralised-loan risk applies in full.
It cannot promise a date
Self-repaying describes the direction of the debt, not its speed. The speed is whatever the collateral produces, and that is not something Corpus controls or can forecast.
Take a concrete case: 10 AAPL at $200.00, so 2,000 USDG of collateral value, with 600 USDG borrowed.
| Vault yield | Gross per year | After the 10% protocol cut | Time to clear 600 USDG |
|---|---|---|---|
| 2% | 40 USDG | 36 USDG | ~16.7 years |
| 4% | 80 USDG | 72 USDG | ~8.3 years |
| 8% | 160 USDG | 144 USDG | ~4.2 years |
Those are not projections. There is no vault, so there is no rate to project; they are arithmetic on hypotheticals, to make the shape of the thing visible.
And note what drives the numerator: yield accrues on your collateral, not on your debt. Borrow more against the same collateral and the repayment rate does not change — only the amount to repay does. The same 2,000 USDG of collateral at 4% retires a 600 USDG debt in about 8.3 years and a 1,000 USDG debt in about 13.9 years. Borrowing at the maximum does not just tighten your liquidation buffer; it lengthens the self-repayment by the same proportion.
The app shows an estimated time to zero derived from the realised rate. Today it reads "Not shrinking", because the realised rate is zero.
It cannot make the yield yours for free
The yield used to repay your loan is your collateral's yield. If you held the tokens in a vault yourself, you would have it. Corpus points it at your debt and keeps 10% of it for doing so, plus the cost of swapping it to USDG.
That is a genuine service — you get liquidity now, with no interest and no deadline, in exchange for the earnings you would otherwise collect later — but it is an exchange, not a gift. Nobody is paying your loan for you.
It cannot turn a vault loss into a smaller debt
Corpus defines yield as vault shares valued above recorded principal, floored at zero. A vault that loses value simply reports no surplus. This is protective in one direction: a vault loss can never increase your debt, and there is no mechanism anywhere in the contracts that raises a debt after it is borrowed.
But floors are not recoveries. If a future earning vault loses principal, the shortfall does not vanish because the accounting refuses to record it — it appears when you try to withdraw and the vault cannot return everything it holds for you. Zero is a floor on the accounting, not a guarantee on the assets.
It cannot harvest what it cannot sell
Harvested yield has to be converted to USDG through an on-chain pool, and Corpus insists on getting at least the oracle value of that yield minus 1%. If the pool cannot fill it, the harvest reverts.
That is the right failure: nothing gets sold at a bad price, and nothing is lost except the repayment you expected. But it means self-repayment depends on an external pool having liquidity at the moment somebody calls harvest. Thin market, no repayment. The debt does not grow; it just stops shrinking.
It cannot stop you from over-borrowing
The protocol enforces a maximum LTV and nothing else. The borrow button is fully enabled at 49.9% on a market where liquidation begins at 60%. There is no advice, no risk questionnaire, no confirmation dialogue asking whether you have thought about a weekend gap.
Self-repayment sounds like it makes leverage safer. It does not. A position borrowed to the limit is exactly as liquidatable in a self-repaying protocol as anywhere else, and now it also takes the longest to repay itself.
It cannot be a hedge, an income product, or a reason to hold
Corpus does not pay you anything. It does not hedge your exposure, it does not generate income, and it does not make holding the collateral a better idea than it was. If you would not hold these tokens without the loan, the loan is not a reason to.
It cannot undo custody, issuer or jurisdiction risk
A Robinhood Stock Token is a claim honoured by a third party. Corpus is indifferent to whether that claim is good. USDG is a third party's stablecoin. And the tokens themselves are not available to US persons and are restricted elsewhere, which is your responsibility to establish and not something the protocol checks.
What it does do
With all of that said, the mechanism does one thing, cleanly: it removes the growing side of a loan.
There is no interest variable in these contracts. There is no maturity date. After the moment you borrow, your debt can only be reduced — by you, by harvested yield, or by a liquidator. That is unusual and it is real, and it is available today even with the yield at zero.
Just call it what it is. Today, Corpus is a zero-interest loan with no deadline. The self-repaying part is built, tested, and waiting for something to harvest.