diff --git a/src/main/java/seedu/address/logic/parser/ClaimCommandParser.java b/src/main/java/seedu/address/logic/parser/ClaimCommandParser.java
index cbb1b77f43a..7104523a016 100644
--- a/src/main/java/seedu/address/logic/parser/ClaimCommandParser.java
+++ b/src/main/java/seedu/address/logic/parser/ClaimCommandParser.java
@@ -29,6 +29,7 @@ public class ClaimCommandParser implements Parser<ClaimCommand> {
     public ClaimCommand parse(String args) throws ParseException {
         requireNonNull(args);
         ArgumentMultimap argMultimap = ArgumentTokenizer.tokenize(args, PREFIX_CLAIM_AMOUNT);
+        argMultimap.verifyNoDuplicatePrefixesFor(PREFIX_CLAIM_AMOUNT);
 
         Index index;
         Claim claim;
diff --git a/src/main/java/seedu/address/model/person/Birthday.java b/src/main/java/seedu/address/model/person/Birthday.java
index e3046502db9..4eea830d552 100644
--- a/src/main/java/seedu/address/model/person/Birthday.java
+++ b/src/main/java/seedu/address/model/person/Birthday.java
@@ -1,17 +1,20 @@
 package seedu.address.model.person;
 
 import static java.util.Objects.requireNonNull;
+import static seedu.address.commons.util.AppUtil.checkArgument;
 
 import java.time.DateTimeException;
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
 
 /**
  * Represents a Person's dob.
  */
 public class Birthday {
     public static final String MESSAGE_CONSTRAINTS =
-            "Invalid date of birth. Please provide date of birth with format: YYYY-MM-DD";
+            "Invalid date of birth. Please provide date of birth with format: YYYY-MM-DD.\n"
+            + "An employee must be at least 13 years old.";
 
     public final String dob;
 
@@ -23,12 +26,8 @@ public class Birthday {
     public Birthday(String dateStr) {
         requireNonNull(dateStr);
         dateStr = dateStr.trim();
-        try {
-            LocalDate.parse(dateStr);
-            dob = dateStr;
-        } catch (DateTimeException e) {
-            throw new IllegalArgumentException(MESSAGE_CONSTRAINTS);
-        }
+        checkArgument(isValidDob(dateStr), MESSAGE_CONSTRAINTS);
+        dob = dateStr;
     }
 
     /**
@@ -37,7 +36,11 @@ public Birthday(String dateStr) {
     public static boolean isValidDob(String test) {
         String dateStr = test.trim();
         try {
-            LocalDate.parse(dateStr);
+            LocalDate birthday = LocalDate.parse(dateStr);
+            LocalDate legalBirthday = LocalDate.now().minusYears(13);
+            if (legalBirthday.until(birthday, ChronoUnit.DAYS) > 0) {
+                return false;
+            }
         } catch (DateTimeException e) {
             return false;
         }
diff --git a/src/main/java/seedu/address/model/person/Money.java b/src/main/java/seedu/address/model/person/Money.java
index 691a70b204f..31756f940d0 100644
--- a/src/main/java/seedu/address/model/person/Money.java
+++ b/src/main/java/seedu/address/model/person/Money.java
@@ -21,13 +21,7 @@ public class Money {
      */
     public Money(String numStr) {
         requireNonNull(numStr);
-        checkArgument(numStr.length() < 14, MESSAGE_CONSTRAINTS);
-        try {
-            Long num = Long.valueOf(numStr);
-            checkArgument(num >= 0 && num <= MAX_VALUE, MESSAGE_CONSTRAINTS);
-        } catch (NumberFormatException e) {
-            throw new IllegalArgumentException(MESSAGE_CONSTRAINTS);
-        }
+        checkArgument(isValidMoney(numStr), MESSAGE_CONSTRAINTS);
         amount = numStr;
     }
 
@@ -35,6 +29,9 @@ public Money(String numStr) {
      * Returns true if a given string is a valid dollar amount.
      */
     public static boolean isValidMoney(String test) {
+        if (test.length() >= 14) {
+            return false;
+        }
         try {
             Long num = Long.valueOf(test);
             return num >= 0 && num <= MAX_VALUE;