diff --git a/hydra-node/test/Hydra/Chain/Direct/Contract/CollectCom.hs b/hydra-node/test/Hydra/Chain/Direct/Contract/CollectCom.hs
index 975f761781a..ae2c2d6ef51 100644
--- a/hydra-node/test/Hydra/Chain/Direct/Contract/CollectCom.hs
+++ b/hydra-node/test/Hydra/Chain/Direct/Contract/CollectCom.hs
@@ -175,6 +175,8 @@ healthyCommitOutput party committed =
 data CollectComMutation
   = -- | Ensures collectCom does not allow any output address but νHead.
     NotContinueContract
+  | -- | Needs to prevent that not all value is collected into the head output.
+    ExtractSomeValue
   | MutateOpenUTxOHash
   | -- | Ensures collectCom cannot collect from an initial UTxO.
     MutateCommitToInitial
@@ -197,6 +199,21 @@ genCollectComMutation (tx, _utxo) =
     [ SomeMutation (Just $ toErrorCode NotPayingToHead) NotContinueContract <$> do
         mutatedAddress <- genAddressInEra testNetworkId
         pure $ ChangeOutput 0 (modifyTxOutAddress (const mutatedAddress) headTxOut)
+    , SomeMutation (Just $ toErrorCode NotAllValueCollected) ExtractSomeValue <$> do
+        -- Remove one lovelace from headOutput, i.e. to "collect dust"
+        -- TODO: select a random asset and amount
+        let removedValue = lovelaceToValue 1
+        -- Add another output which would extract the 'removedValue'. The ledger
+        -- would check for this, and this is needed because the way we implement
+        -- collectCom checks.
+        extractionTxOut <- do
+          someAddress <- genAddressInEra testNetworkId
+          pure $ TxOut someAddress removedValue TxOutDatumNone ReferenceScriptNone
+        pure $
+          Changes
+            [ ChangeOutput 0 $ modifyTxOutValue (\v -> v <> negateValue removedValue) headTxOut
+            , AddOutput extractionTxOut
+            ]
     , SomeMutation (Just $ toErrorCode IncorrectUtxoHash) MutateOpenUTxOHash . ChangeOutput 0 <$> mutateUTxOHash
     , SomeMutation (Just $ toErrorCode MissingCommits) MutateNumberOfParties <$> do
         moreParties <- (: healthyOnChainParties) <$> arbitrary
@@ -206,6 +223,9 @@ genCollectComMutation (tx, _utxo) =
             , ChangeOutput 0 $ mutatedPartiesHeadTxOut moreParties headTxOut
             ]
     , SomeMutation (Just $ toErrorCode STNotSpent) MutateHeadId <$> do
+        -- XXX: This mutation is unrealistic. It would only change the headId in
+        -- the value, but not in the datum. This is not allowed by the protocol
+        -- prior to this transaction.
         illedHeadResolvedInput <-
           mkHeadOutput
             <$> pure testNetworkId
diff --git a/hydra-node/test/Hydra/Chain/Direct/Contract/Mutation.hs b/hydra-node/test/Hydra/Chain/Direct/Contract/Mutation.hs
index 3c5fbd3ca5e..692cdd39dcf 100644
--- a/hydra-node/test/Hydra/Chain/Direct/Contract/Mutation.hs
+++ b/hydra-node/test/Hydra/Chain/Direct/Contract/Mutation.hs
@@ -265,8 +265,10 @@ data Mutation
     -- both the 'DatumHash' in the UTxO context and the map of 'DatumHash' to
     -- 'Datum' in the transaction's witnesses.
     ChangeInputHeadDatum Head.State
-  | -- | Adds given output to the transaction's outputs.
+  | -- | Adds given output as first transaction output.
     PrependOutput (TxOut CtxTx)
+  | -- | Adds given output as last transaction output.
+    AddOutput (TxOut CtxTx)
   | -- | Removes given output from the transaction's outputs.
     RemoveOutput Word
   | -- | Drops the given input from the transaction's inputs
@@ -349,6 +351,10 @@ applyMutation mutation (tx@(Tx body wits), utxo) = case mutation of
     ( alterTxOuts (txOut :) tx
     , utxo
     )
+  AddOutput txOut ->
+    ( alterTxOuts (<> [txOut]) tx
+    , utxo
+    )
   RemoveOutput ix ->
     ( alterTxOuts (removeAt ix) tx
     , utxo
diff --git a/hydra-plutus/src/Hydra/Contract/Head.hs b/hydra-plutus/src/Hydra/Contract/Head.hs
index 3c02a4f4dcf..519206b6d30 100644
--- a/hydra-plutus/src/Hydra/Contract/Head.hs
+++ b/hydra-plutus/src/Hydra/Contract/Head.hs
@@ -158,13 +158,14 @@ checkCollectCom ::
   (ContestationPeriod, [Party], CurrencySymbol) ->
   Bool
 checkCollectCom ctx@ScriptContext{scriptContextTxInfo = txInfo} (contestationPeriod, parties, headId) =
-  mustNotMintOrBurn txInfo
-    && mustCollectUtxoHash
+  mustCollectUtxoHash
     && mustNotChangeParameters
+    && mustCollectAllValue
+    -- XXX: Is this really needed? If yes, why not check on the output?
+    && traceIfFalse $(errorCode STNotSpent) (hasST headId val)
     && everyoneHasCommitted
     && mustBeSignedByParticipant ctx headId
-    -- FIXME: does not check all value collected
-    && traceIfFalse $(errorCode STNotSpent) (hasST headId val)
+    && mustNotMintOrBurn txInfo
  where
   mustCollectUtxoHash =
     traceIfFalse $(errorCode IncorrectUtxoHash) $
@@ -176,6 +177,14 @@ checkCollectCom ctx@ScriptContext{scriptContextTxInfo = txInfo} (contestationPer
         && contestationPeriod' == contestationPeriod
         && headId' == headId
 
+  mustCollectAllValue =
+    traceIfFalse $(errorCode NotAllValueCollected) $
+      -- NOTE: Instead of checking the head output val' against all collected
+      -- value, we do ensure the output value is all non collected value - fees.
+      -- This makes the script not scale badly with number of participants as it
+      -- would commonly only be a small number of inputs/outputs to pay fees.
+      otherValueOut == notCollectedValueIn - txInfoFee txInfo
+
   (parties', utxoHash, contestationPeriod', headId') =
     -- XXX: fromBuiltinData is super big (and also expensive?)
     case fromBuiltinData @DatumType $ getDatum (headOutputDatum ctx) of
@@ -191,30 +200,37 @@ checkCollectCom ctx@ScriptContext{scriptContextTxInfo = txInfo} (contestationPer
 
   headAddress = getHeadAddress ctx
 
-  val =
-    maybe mempty (txOutValue . txInInfoResolved) $ findOwnInput ctx
-
   everyoneHasCommitted =
     traceIfFalse $(errorCode MissingCommits) $
       nTotalCommits == length parties
 
-  (collectedCommits, nTotalCommits) =
+  val = maybe mempty (txOutValue . txInInfoResolved) $ findOwnInput ctx
+
+  otherValueOut =
+    case txInfoOutputs txInfo of
+      -- NOTE: First output must be head output
+      (_ : rest) -> foldMap txOutValue rest
+      _ -> mempty
+
+  -- NOTE: We do keep track of the value we do not want to collect as this is
+  -- typically less, ideally only a single other input with only ADA in it.
+  (collectedCommits, nTotalCommits, notCollectedValueIn) =
     foldr
       extractAndCountCommits
-      ([], 0)
+      ([], 0, mempty)
       (txInfoInputs txInfo)
 
-  extractAndCountCommits TxInInfo{txInInfoResolved} (commits, nCommits)
+  extractAndCountCommits TxInInfo{txInInfoResolved} (commits, nCommits, notCollected)
     | isHeadOutput txInInfoResolved =
-      (commits, nCommits)
+      (commits, nCommits, notCollected)
     | hasPT headId txInInfoResolved =
       case commitDatum txInfo txInInfoResolved of
         Just commit@Commit{} ->
-          (commit : commits, succ nCommits)
+          (commit : commits, succ nCommits, notCollected)
         Nothing ->
-          (commits, succ nCommits)
+          (commits, succ nCommits, notCollected)
     | otherwise =
-      (commits, nCommits)
+      (commits, nCommits, notCollected <> txOutValue txInInfoResolved)
 
   isHeadOutput txOut = txOutAddress txOut == headAddress
 {-# INLINEABLE checkCollectCom #-}
@@ -261,8 +277,6 @@ checkClose ctx parties initialUtxoHash sig cperiod headPolicyId =
     && checkSnapshot
     && mustBeSignedByParticipant ctx headPolicyId
     && mustInitializeContesters
-    -- XXX: missing to trace for this error code
-    && hasST headPolicyId val
     && mustPreserveValue
     && mustNotChangeParameters
  where
@@ -370,11 +384,6 @@ checkContest ctx contestationDeadline contestationPeriod parties closedSnapshotN
     && checkSignedParticipantContestOnlyOnce
     && mustBeWithinContestationPeriod
     && mustUpdateContesters
-    -- XXX: This check is redundant and can be removed,
-    -- because is enough to check that the value is preserved.
-    -- Remember we are comming from a valid Closed state,
-    -- having already checked that the ST is present.
-    && hasST headId val
     && mustPushDeadline
     && mustNotChangeParameters
     && mustPreserveValue
diff --git a/hydra-plutus/src/Hydra/Contract/HeadError.hs b/hydra-plutus/src/Hydra/Contract/HeadError.hs
index 67b0f52a8c4..681fb3f5cc1 100644
--- a/hydra-plutus/src/Hydra/Contract/HeadError.hs
+++ b/hydra-plutus/src/Hydra/Contract/HeadError.hs
@@ -44,6 +44,7 @@ data HeadError
   | SignatureVerificationFailed
   | PartySignatureVerificationFailed
   | NotPayingToHead
+  | NotAllValueCollected
   deriving (Show)
 
 instance ToErrorCode HeadError where
@@ -87,3 +88,4 @@ instance ToErrorCode HeadError where
     SignatureVerificationFailed -> "H35"
     PartySignatureVerificationFailed -> "H36"
     NotPayingToHead -> "H37"
+    NotAllValueCollected -> "H38"