diff --git a/server/src/lib/score-import/framework/score-importing/validate-score.test.ts b/server/src/lib/score-import/framework/score-importing/validate-score.test.ts
new file mode 100644
index 000000000..c74fd96c0
--- /dev/null
+++ b/server/src/lib/score-import/framework/score-importing/validate-score.test.ts
@@ -0,0 +1,24 @@
+import { ValidateScore } from "./validate-score";
+import { ONE_DAY } from "lib/constants/time";
+import t from "tap";
+import { Testing511SPA, TestingIIDXSPScore } from "test-utils/test-data";
+
+t.test("#ValidateScore", (t) => {
+	t.test("Should reject scores in the future", (t) => {
+		t.throws(
+			() => {
+				ValidateScore(
+					{ ...TestingIIDXSPScore, timeAchieved: Date.now() + ONE_DAY * 2 },
+					Testing511SPA
+				);
+			},
+			{
+				message: "Invalid timestamp: score happens in the future.",
+			}
+		);
+
+		t.end();
+	});
+
+	t.end();
+});
diff --git a/server/src/lib/score-import/framework/score-importing/validate-score.ts b/server/src/lib/score-import/framework/score-importing/validate-score.ts
index 00a1b9f17..cabb408a0 100644
--- a/server/src/lib/score-import/framework/score-importing/validate-score.ts
+++ b/server/src/lib/score-import/framework/score-importing/validate-score.ts
@@ -1,18 +1,27 @@
 import { InvalidScoreFailure } from "../common/converter-failures";
 import { GPT_SERVER_IMPLEMENTATIONS } from "game-implementations/game-implementations";
 import { RunValidators } from "game-implementations/games/_common";
+import { ONE_HOUR } from "lib/constants/time";
 import { GetGPTConfig, GetGPTString } from "tachi-common";
 import type { ChartDocument, GPTString, ScoreDocument } from "tachi-common";
 import type { ConfScoreMetric } from "tachi-common/types/metrics";
 
 /**
- * Checks if a score passes all of its validation checks. This tests gpt specific
- * things, like whether this passes the validators defined in gptConfig, or whether
- * it passes the chart-dependent validators defined in the gpt server implementation.
+ * Checks if a score passes all of its validation checks.
  *
  * @returns nothing. This will throw an InvalidScoreFailure on error.
  */
 export function ValidateScore(score: ScoreDocument, chart: ChartDocument): void {
+	const leniency = ONE_HOUR * 24;
+
+	if (score.timeAchieved !== null && score.timeAchieved > Date.now() + leniency) {
+		throw new InvalidScoreFailure("Invalid timestamp: score happens in the future.");
+	}
+
+	ValidateScoreGameSpecific(score, chart);
+}
+
+function ValidateScoreGameSpecific(score: ScoreDocument, chart: ChartDocument): void {
 	const gptString = GetGPTString(score.game, score.playtype);
 	const gptConfig = GetGPTConfig(gptString);
 	const gptImpl = GPT_SERVER_IMPLEMENTATIONS[gptString];