CLO Coverage Tests: OC and IC

A CLO issues several layers of debt against one loan portfolio, from AAA-rated senior notes down through mezzanine tranches to unrated equity. Nobody wants to wait for a full annual audit to find out the collateral has quietly deteriorated. So every deal builds in monthly or quarterly self-checks that automatically redirect cash the moment the numbers move against bondholders.

The two ratios

The OC test at a given tranche is:

$$OC = \frac{\text{Collateral Principal Balance}}{\text{Debt Balance at or above this tranche}}$$

In words: how much loan collateral, in face value, sits behind every dollar of debt at or senior to this tranche. A ratio above 100% (haircutting defaulted or low-priced loans first) means there's a cushion; below the deal's required threshold, the test fails.

The IC test is analogous but uses cash flows instead of balances:

$$IC = \frac{\text{Interest Collected on Collateral}}{\text{Interest Owed on Notes}}$$

In words: is the loan portfolio actually generating enough cash interest each period to cover the coupons owed, regardless of what the face-value balances look like.

Worked example

A CLO tranche requires a 120% OC test. The rated debt at or above that tranche totals $300 million. The collateral pool's performing balance is $348 million. The OC ratio is $348 / 300 = 116\%$ — below the 120% threshold, so the test fails. The waterfall responds automatically: instead of releasing cash to equity and junior tranches this period, principal proceeds are redirected to pay down the senior notes. If $18 million of notes gets paid down, the ratio becomes $348 / 282 \approx 123\%$, curing the test and letting distributions to equity resume the following period.

What this means in practice

Coverage tests are the first line of defense for senior noteholders, tripping automatically long before any loan actually defaults outright — a handful of loans trading down or getting downgraded below the deal's ratings floor is often enough. Equity investors watch these tests closely because a triggered OC test cuts off their distributions immediately, even if the underlying portfolio never technically defaults.