diff --git a/packages/sourcecred/src/core/credequate/scoredContribution.js b/packages/sourcecred/src/core/credequate/scoredContribution.js
index eccb7b365..0caeeaee2 100644
--- a/packages/sourcecred/src/core/credequate/scoredContribution.js
+++ b/packages/sourcecred/src/core/credequate/scoredContribution.js
@@ -112,6 +112,37 @@ export const scoreContribution = (
   };
 };
 
+export function expressionHasSubkey(
+  expression: Expression | ScoredExpression,
+  key: string,
+  subkey: string
+): boolean {
+  for (const weightOperand of expression.weightOperands) {
+    if (weightOperand.key === key && weightOperand.subkey === subkey)
+      return true;
+  }
+  for (const expressionOperand of expression.expressionOperands) {
+    if (expressionHasSubkey(expressionOperand, key, subkey)) return true;
+  }
+  return false;
+}
+
+export function* findContributionsBySubkey<
+  T: Contribution | ScoredContribution
+>(contributions: Iterable<T>, key: string, subkey: string): Iterable<T> {
+  for (const contribution of contributions) {
+    if (expressionHasSubkey(contribution.expression, key, subkey))
+      yield contribution;
+    else {
+      for (const participant of contribution.participants) {
+        for (const share of participant.shares) {
+          if (share.key === key && share.subkey === subkey) yield contribution;
+        }
+      }
+    }
+  }
+}
+
 export function* scoreContributions(
   contributions: Iterable<Contribution>,
   configs: $ReadOnlyArray<Config>
diff --git a/packages/sourcecred/src/core/credequate/scoredContribution.test.js b/packages/sourcecred/src/core/credequate/scoredContribution.test.js
new file mode 100644
index 000000000..49f00f9bc
--- /dev/null
+++ b/packages/sourcecred/src/core/credequate/scoredContribution.test.js
@@ -0,0 +1,92 @@
+// @flow
+
+import {findContributionsBySubkey} from "./scoredContribution.js";
+import {type Contribution, type Expression} from "./contribution.js";
+import {NodeAddress} from "../graph.js";
+
+describe("core/credequate/scoredContribution", () => {
+  const weightOperand0 = {
+    key: ":key0:",
+    subkey: ":subkey0:",
+  };
+
+  const weightOperand1 = {
+    key: ":key1:",
+    subkey: ":subkey1:",
+  };
+  const weightOperand2 = {
+    key: ":key2:",
+    subkey: ":subkey2:",
+  };
+
+  const weightOperand3 = {
+    key: ":key3:",
+    subkey: ":subkey3:",
+  };
+  const weightOperand4 = {
+    key: ":key4:",
+    subkey: ":subkey4:",
+  };
+
+  const weightOperand5 = {
+    key: ":key5:",
+    subkey: ":subkey5:",
+  };
+
+  const expression: Expression = {
+    operator: "ADD",
+    expressionOperands: [],
+    description: "",
+    weightOperands: [weightOperand0, weightOperand1],
+  };
+
+  const participants = [
+    {
+      id: NodeAddress.fromParts(["amrro"]),
+      shares: [weightOperand2, weightOperand3],
+    },
+    {
+      id: NodeAddress.fromParts(["thena"]),
+      shares: [weightOperand4, weightOperand5],
+    },
+  ];
+
+  const contribution: Contribution = {
+    id: "one",
+    plugin: "discord",
+    type: "",
+    timestampMs: 0,
+    expression,
+    participants,
+  };
+
+  it("should find contributions with matching expression's key & subkey", () => {
+    const iter = findContributionsBySubkey(
+      [contribution],
+      expression.weightOperands[0].key,
+      expression.weightOperands[0].subkey ?? ""
+    );
+
+    const contributions = Array.from(iter);
+    expect(contributions).toEqual([contribution]);
+  });
+
+  it("should find contributions with matching participant's share's key & subkey", () => {
+    const iter = findContributionsBySubkey(
+      [contribution],
+      contribution.participants[0].shares[0].key,
+      contribution.participants[0].shares[0].subkey ?? ""
+    );
+
+    const contributions = Array.from(iter);
+    expect(contributions).toEqual([contribution]);
+  });
+
+  it("shouldn't find any contributions", () => {
+    const iter = findContributionsBySubkey([contribution], "channel", "abcd");
+
+    const contributions = Array.from(iter);
+    console.log(contributions);
+    expect(contributions).toEqual([]);
+  });
+});