diff --git a/services/registration/src/common/adjustScores.ts b/services/registration/src/common/adjustScores.ts
index cd7c556..557cae9 100644
--- a/services/registration/src/common/adjustScores.ts
+++ b/services/registration/src/common/adjustScores.ts
@@ -26,6 +26,11 @@ type CriteriaScores = {
   score: number;
 }[];
 
+// distinguishable referral bonus (points should never be this high for any other reason)
+// can we make a separate field for this? yes, however that requires handling a bunch of
+// edge cases so surely its okay to be lazy for now
+export const REFERRAL_BONUS = 100;
+
 /** The minimum grading score an essay can get. */
 const MIN_GRADING_SCORE = 1;
 /** The maximum grading score an essay can get. */
diff --git a/services/registration/src/routes/grading.ts b/services/registration/src/routes/grading.ts
index ad0c376..55a235f 100644
--- a/services/registration/src/routes/grading.ts
+++ b/services/registration/src/routes/grading.ts
@@ -6,16 +6,31 @@ import { Types } from "mongoose";
 import _ from "lodash";
 
 import { ApplicationModel, Essay, StatusType } from "../models/application";
+import { ReferralModel, ReferralStatusType } from "../models/referral";
 import { GraderModel } from "../models/grader";
 import { Review, ReviewModel } from "../models/review";
 import { BranchModel, BranchType, GradingGroupType } from "../models/branch";
 import { calibrationQuestionMapping, rubricMapping } from "../config";
-import { getCalibrationMapping } from "../common/adjustScores";
+import { getCalibrationMapping, REFERRAL_BONUS } from "../common/adjustScores";
 
 const MAX_REVIEWS_PER_ESSAY = 2;
 // NOTE: No. of essays for each application. As such, will need to be updated whenever we add/remove essays.
 const ESSAY_COUNT = 4;
 
+async function checkForReferralBonus(email?: string, hexathon?: Types.ObjectId) {
+  if (!email || !hexathon) {
+    return 0;
+  }
+
+  const referral = await ReferralModel.exists({
+    hexathon,
+    "status": ReferralStatusType.SUBMITTED,
+    "referralData.email": new RegExp(`^${_.escapeRegExp(email.trim())}$`, "i"),
+  });
+
+  return referral ? REFERRAL_BONUS : 0;
+}
+
 type AggregatedEssay = {
   applicationId: string;
   applicationBranch: string;
@@ -304,7 +319,9 @@ gradingRouter.route("/actions/submit-review").post(
       if (allEssayReviews.length >= MAX_REVIEWS_PER_ESSAY * ESSAY_COUNT) {
         application.gradingComplete = true;
         const sumScores = allEssayReviews.reduce((prev, review) => prev + review.adjustedScore, 0);
-        application.finalScore = sumScores / allEssayReviews.length;
+        const baseScore = sumScores / allEssayReviews.length;
+        const referralBonus = await checkForReferralBonus(application.email, application.hexathon);
+        application.finalScore = baseScore + referralBonus;
         await application.save();
       }
 
diff --git a/services/registration/src/routes/referrals.ts b/services/registration/src/routes/referrals.ts
index 905bae5..365d0c4 100644
--- a/services/registration/src/routes/referrals.ts
+++ b/services/registration/src/routes/referrals.ts
@@ -6,9 +6,50 @@ import { FilterQuery, isValidObjectId, Types } from "mongoose";
 
 import { validateReferralData } from "../common/util";
 import { Referral, ReferralModel, ReferralStatusType } from "../models/referral";
+import { ApplicationModel, StatusType } from "../models/application";
+import { REFERRAL_BONUS } from "../common/adjustScores";
 
 export const referralRouter = express.Router();
 
+/*
+  The referral bonus gets applied after the last grader's review is submitted,
+  this handles the cases where someone is referred after their application is graded
+*/
+async function applyReferralBonus(
+  email?: string,
+  hexathon?: Types.ObjectId,
+  referralId?: Types.ObjectId
+) {
+  if (!email || !hexathon || !referralId) {
+    return;
+  }
+
+  const emailRegex = new RegExp(`^${_.escapeRegExp(email.trim())}$`, "i");
+
+  const application = await ApplicationModel.findOne({
+    hexathon,
+    email: emailRegex,
+    status: { $ne: StatusType.DRAFT },
+  });
+
+  if (!application || !application.gradingComplete) {
+    return;
+  }
+
+  const alreadyHasBonus = await ReferralModel.exists({
+    hexathon,
+    "referralData.email": emailRegex,
+    "status": ReferralStatusType.SUBMITTED,
+    "_id": { $ne: referralId },
+  });
+  if (alreadyHasBonus) {
+    return;
+  }
+
+  application.finalScore += REFERRAL_BONUS;
+  await application.save();
+}
+
 referralRouter.route("/actions/create-referral").post(
   checkAbility("create", "Referral"),
   asyncHandler(async (req, res) => {
@@ -255,6 +296,10 @@ referralRouter.route("/:id/actions/submit-referral").post(
       throw new BadRequestError("No referral exists with this id or you do not have permission.");
     }
 
+    if (existingReferral.status !== ReferralStatusType.DRAFT) {
+      throw new BadRequestError("This referral has already been submitted.");
+    }
+
     let resume;
     if (existingReferral.referralData.resume) {
       resume = await apiCall(
@@ -281,6 +326,12 @@ referralRouter.route("/:id/actions/submit-referral").post(
       { new: true, runValidators: true }
     );
 
+    await applyReferralBonus(
+      existingReferral.referralData.email,
+      existingReferral.hexathon,
+      existingReferral._id
+    );
+
     return res.sendStatus(204);
   })
 );