FRM Exam Part II · Netting, Close-out and Related Aspects

Collateral, CSA and Related Credit Mitigants Explained

Updated 11 October 2026 · Fact-checked

A credit support annex (CSA) is the part of an ISDA agreement that sets collateral rules for a netting set. Collateral is called when net exposure exceeds the threshold, in steps of at least the minimum transfer amount. Residual risk is the exposure that can build up over the margin period of risk.

Understand Collateral, CSA and Related Credit Mitigants

Netting reduces many trades with one counterparty to a single net amount. Collateral goes one step further. It gives you assets you can keep or sell if the counterparty defaults. Netting and collateral work together: collateral is called against the net value of the netting set, not trade by trade.

The credit support annex (CSA) is the legal document that sets how collateral works. It states which assets are eligible, what haircuts apply, how often you call margin, and the threshold, minimum transfer amount (MTA), and independent amount. A CSA can be one-way or two-way. Most dealer-to-dealer CSAs are two-way.

The threshold is the amount of uncollateralised exposure you accept before any collateral is due. If the threshold is ₹0 or USD 0, exposure is collateralised from the first dollar. The MTA is a small-transfer filter. Collateral moves only when the required change is at least the MTA. Both features leave some exposure uncollateralised. The independent amount (initial margin) is posted on top of variation margin as a buffer.

Even with daily margining, you are not fully protected. After the last margin call you received, the counterparty defaults. You then need time to notice the default, close out and replace trades, and sell the collateral. That time is the margin period of risk (MPOR). Market moves during the MPOR can create a loss that collateral does not cover. Basel sets a minimum MPOR of 10 business days for daily-margined OTC derivatives netting sets, and longer in some cases, such as large or illiquid netting sets or disputes.

So the residual exposure on a collateralised netting set is roughly: the threshold plus MTA effects, plus the change in net value over the MPOR, minus any initial margin held. Collateral also brings its own risks: haircuts for collateral price and FX volatility, wrong-way risk if the collateral is linked to the counterparty, and legal risk if the collateral cannot be enforced. The value of netting and collateral depends on enforceable close-out in the relevant jurisdiction.

Key formulas to remember

Collateral required (variation margin): Required = max(0, Net exposure − Threshold); Net exposure is the mark-to-market of the whole netting set. Use the threshold of the party that is owed.
Collateral call: Call = Required − Collateral held, if |Call| ≥ MTA; otherwise no transfer; The MTA applies to the change in collateral. Some CSAs also use rounding.
Haircut-adjusted collateral value: Value = Market value × (1 − haircut); Haircuts cover price volatility and FX mismatch of the collateral asset.
Exposure after collateral: Exposure = max(0, V(t+MPOR) − C(t)); V is net value at default close-out. C is collateral held at the last margin call.
Exposure with initial margin: Exposure = max(0, V(t+MPOR) − VM − IM); IM absorbs part of the MPOR move, so it reduces exposure.
MPOR scaling of volatility: σ(MPOR) = σ(daily) × √(MPOR in days); Assumes independent daily changes. Longer MPOR raises residual exposure by the square root of time.

How to solve Collateral, CSA and Related Credit Mitigants questions

Use this order for any CSA or collateral question. It forces you to separate legal netting, collateral terms and the MPOR risk.

1Identify the netting set and compute its net mark-to-market. Offset gains and losses only if netting is enforceable.
2Read the CSA terms: threshold, MTA, independent amount, eligible collateral, haircuts and margin frequency.
3Compute required collateral as net exposure minus threshold, floored at zero. Then compare with collateral already held.
4Apply the MTA to the change. If the call is below the MTA, no transfer occurs.
5Apply haircuts to non-cash collateral to get its effective value.
6Estimate residual risk over the MPOR. Use the exposure change over the MPOR, or scale volatility by √MPOR, and add any uncollateralised threshold.
7Interpret: state what is still unprotected and which term (threshold, MTA, MPOR, haircut, legal risk) drives it.

Quickest way: Three-line collateral check

When to use it: Use when a question gives you exposure, threshold and MTA and asks for a margin call or uncovered amount.

Subtract the threshold from net exposure. Floor at zero. This is the target collateral.
Subtract collateral already held. If the result is smaller than the MTA in absolute value, the answer is no transfer.
For the uncovered amount, add the threshold (or the amount below it) and the MPOR move. Scale volatility by √days if needed.

Common mistakes in Collateral, CSA and Related Credit Mitigants

Calling collateral on each trade instead of on the netting set
Students forget that the CSA works on the net portfolio value.
Fix: Net the trades first, then apply threshold and MTA once.
Treating the MTA as a deductible from exposure
The MTA sounds like the threshold.
Fix: The threshold reduces required collateral. The MTA only blocks small transfers. Apply the MTA to the call, not to exposure.
Assuming daily margining means zero exposure
Collateral feels like full protection.
Fix: Exposure can still build up over the MPOR after the last margin call, plus any threshold and haircuts.
Using a 1-day horizon for the MPOR
Margin is called daily, so students equate the two.
Fix: MPOR covers default detection, close-out and replacement. Basel's minimum for daily-margined OTC derivatives is 10 business days, and it can be longer.
Ignoring haircuts or wrong-way risk on collateral
Cash is the default mental picture.
Fix: Apply haircuts to securities and FX mismatch. Flag collateral issued by, or correlated with, the counterparty.
Assuming collateral works without legal enforceability
Focus on numbers over documents.
Fix: State that netting and collateral benefits require enforceable close-out and collateral rights in the relevant jurisdiction.

Worked examples

Example 1

A two-way CSA has a threshold of USD 2 million for the counterparty and an MTA of USD 500,000. Your net exposure to the counterparty is USD 7.3 million. The counterparty currently holds posted USD 4.6 million with you. Daily margining applies. What call do you make?

Show the solution

Required collateral = 7.3 − 2.0 = USD 5.3 million.
Collateral held = USD 4.6 million.
Call = 5.3 − 4.6 = USD 0.7 million.
Compare with the MTA of USD 0.5 million. 0.7 is at least 0.5, so the transfer occurs.

Answer: You call USD 700,000 of additional collateral.

Example 2

A bank has a net exposure of USD 10 million to a counterparty and holds exactly the required cash collateral under a CSA with zero threshold and zero MTA. The net portfolio's daily value volatility is USD 0.6 million. Assume independent daily changes and an MPOR of 10 days. Using one standard deviation, what is the residual exposure over the MPOR, and how does it change if the MPOR rises to 20 days?

Show the solution

Collateral equals the exposure at the last call, so the starting uncovered amount is zero.
σ over 10 days = 0.6 × √10 = 0.6 × 3.1623 = USD 1.897 million.
σ over 20 days = 0.6 × √20 = 0.6 × 4.4721 = USD 2.683 million.
Ratio = 2.683 ÷ 1.897 = 1.414, which is √2.

Answer: Residual exposure is about USD 1.90 million at a 10-day MPOR and about USD 2.68 million at 20 days. Doubling the MPOR raises it by √2, about 41%, not by 100%.

Exam tips

Check the order: net first, subtract threshold, then compare the change with the MTA.
If a question asks what daily margining leaves uncovered, the answer is the MPOR move plus threshold and haircut effects.
Remember that a longer MPOR raises exposure by the square root of time, not linearly, when changes are independent.
Look for wrong-way risk or illiquid collateral clues. They often signal a longer MPOR or larger haircut.
Watch the direction: a threshold held by the counterparty reduces what they must post to you.

Practice questions from Netting, Close-out and Related Aspects

Collateral, CSA and Related Credit Mitigants: frequently asked questions

What is a credit support annex in simple terms?

It is the part of an ISDA agreement that sets collateral rules. It covers eligible assets, haircuts, thresholds, MTAs and how often margin is called. It applies to the whole netting set.

What is the difference between threshold and minimum transfer amount?

The threshold is exposure you leave uncollateralised before any collateral is due. The MTA is the smallest collateral movement that triggers a transfer. The threshold reduces the amount required, while the MTA only stops small transfers.

What is the margin period of risk?

It is the time between the last margin call you received and the point where you have closed out and replaced the trades after a default. Market moves in this window create residual exposure. Basel sets a minimum of 10 business days for daily-margined OTC derivatives netting sets.

How does collateral work with netting sets?

Collateral is calculated against the net value of the netting set. Netting must be legally enforceable for this to hold. If it is not, exposure is measured trade by trade and collateral protection weakens.