AT1 Bonds Explained: The Perpetual Debt That Can Be Written Off
AT1 bonds pay a higher coupon than almost anything else in the Indian bond market, and it isn’t free. They have no fixed maturity date, the issuer can skip the coupon at its own discretion, and — as roughly ₹8,415 crore of Yes Bank AT1 bondholders discovered in March 2020 — the entire principal can be written to zero while equity shareholders keep something. This article explains the structure behind that risk.
What AT1 actually stands for
Additional Tier 1 (AT1) capital is a category defined under the Basel III banking regulations, which the Reserve Bank of India has adopted for Indian banks. Banks need a buffer of loss-absorbing capital beyond their core equity, and AT1 bonds (also called Perpetual Debt Instruments, or PDIs) are how banks raise part of that buffer from the debt market instead of issuing more equity.
On RetailBonds.in, these bonds carry no fixed maturity date — the metrics tile on a bond’s detail page shows Perpetual instead of a years-to-maturity count, the same treatment applied to any bond filed with a placeholder maturity year of 2099 or later.
The perpetual structure — and the call date trap
AT1 bonds have no contractual maturity date. What they do have is a call option, typically 5 or 10 years after issuance, which lets the bank redeem the bond at its discretion. Because banks have historically exercised these calls on schedule, the market has treated the call date as an informal maturity — pricing and quoting the bond as if it will be redeemed then.
That assumption is not contractual. A bank under capital stress can skip the call, and the bond simply continues as perpetual debt. This happened to several Indian bank AT1 issues around periods of sector stress — investors who had priced the bond to its expected call date found themselves holding an instrument with no defined end date at all.
Coupons are discretionary, not obligatory
Unlike a standard NCD, where missing a coupon payment is a default, an AT1 issuer can skip the coupon entirely at its own discretion — with no default triggered and no right for bondholders to sue for the missed payment. RBI guidelines also require the bank to skip AT1 coupons if paying them would breach minimum regulatory capital ratios, or if the bank has insufficient distributable reserves in a given year.
This is a structural feature, not a stress signal alone — but it means the high coupon on an AT1 bond compensates for a payment that is conditional on the issuer’s discretion and capital position, not a fixed contractual obligation the way a corporate NCD coupon is.
The write-down / write-off trigger
The feature that separates AT1 from every other bond type on this site is the loss-absorption trigger. Under Basel III / RBI rules, an AT1 bond must be written down (partially or fully) or converted to equity if either of these events occurs:
- Point of Non-Viability (PONV): The RBI determines the bank would become non-viable without a write-down or public sector injection of capital.
- Common Equity Tier 1 (CET1) ratio breach: If the bank’s core equity capital ratio falls below a pre-specified trigger level (typically 5.5% pre-2019, 6.125% under later norms), the AT1 bonds absorb losses automatically — before any equity shareholder loses their entire investment.
This is the inversion that makes AT1 unusual: in a normal liquidation, equity holders are wiped out before any bondholder. Under an AT1 write-down, bondholders can be written down to zero while the bank continues operating and existing equity retains some value — the opposite of the usual capital-structure priority.
Yes Bank, March 2020 — what actually happened
In March 2020, as part of a Reserve Bank of India-led reconstruction scheme for Yes Bank, the bank’s entire outstanding AT1 bond issuance — approximately ₹8,415 crore across multiple series — was written down to zero. Equity shareholders were diluted heavily but not wiped out entirely; a consortium led by State Bank of India infused fresh capital and took a controlling stake in the reconstructed bank.
AT1 bondholders challenged the write-down in the Bombay High Court, arguing the RBI scheme should have required equity to absorb losses first. The write-down was ultimately upheld by courts as consistent with the terms disclosed in the bonds’ own offer documents — the loss-absorption clause had been there from issuance, even though it had never been tested in India before 2020.
The lesson is not that AT1 bonds are uniquely dangerous instruments to avoid entirely — large institutional investors buy them for the yield pickup with full awareness of the trigger. The lesson is that the write-down clause is real, contractual, and has already been exercised once in India, not a theoretical tail risk confined to textbooks.
AT1 vs a standard perpetual bond vs a regular NCD
| Factor | AT1 Bond | Regular NCD |
|---|---|---|
| Maturity | None (perpetual, callable) | Fixed date |
| Coupon | Discretionary, can be skipped without default | Contractual; missed payment is a default |
| Loss absorption | Written down/off on PONV or CET1 breach, ahead of equity wipeout | Standard creditor priority in liquidation |
| Typical issuer | Banks (Basel III capital instruments) | Any corporate, NBFC, or PSU |
| Typical coupon premium | Materially higher, reflecting the above | Reflects issuer credit quality only |
What to check before holding an AT1 bond
- Issuer’s CET1 ratio and its distance from the trigger level — the closer the bank sits to the regulatory minimum, the closer the loss-absorption clause is to being tested.
- Whether the call date has been priced as an assumed maturity — check the bond’s offer document for whether the call is at the issuer’s sole discretion (it always is under Basel III).
- The issuer’s coupon history — has the bank skipped or deferred AT1 coupons on any series before?
- Current credit rating and rating trend — see the bond’s rating action history for downgrades, which typically precede capital stress.
- Concentration — AT1 bonds should be a small allocation given the binary write-down risk, not a yield-chasing core holding.
Key takeaways
- AT1 (Additional Tier 1) bonds are Basel III bank capital instruments with no fixed maturity, a discretionary call date, and discretionary coupons.
- They can be written down or converted to equity if the issuing bank breaches its CET1 capital ratio or is declared non-viable by the RBI — ahead of an equity wipeout, not after one.
- Yes Bank’s 2020 AT1 write-off (~₹8,415 crore) demonstrated this is a real, exercised clause in India, upheld by courts as consistent with the bonds’ own disclosed terms.
- The elevated coupon on an AT1 bond compensates for structural risks a standard NCD investor is not used to underwriting — check CET1 headroom and coupon-skip history before treating the coupon as reliable income.
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