diff --git a/wpilibc/src/main/native/cpp/Timer.cpp b/wpilibc/src/main/native/cpp/Timer.cpp
index 62a05ee2d2..f5bdb93125 100644
--- a/wpilibc/src/main/native/cpp/Timer.cpp
+++ b/wpilibc/src/main/native/cpp/Timer.cpp
@@ -63,7 +63,7 @@ void Timer::Stop() {
 }
 
 bool Timer::HasElapsed(units::second_t period) const {
-  return Get() > period;
+  return Get() >= period;
 }
 
 bool Timer::HasPeriodPassed(units::second_t period) {
@@ -71,7 +71,7 @@ bool Timer::HasPeriodPassed(units::second_t period) {
 }
 
 bool Timer::AdvanceIfElapsed(units::second_t period) {
-  if (Get() > period) {
+  if (Get() >= period) {
     // Advance the start time by the period.
     m_startTime += period;
     // Don't set it to the current time... we want to avoid drift.
diff --git a/wpilibc/src/test/native/cpp/TimerTest.cpp b/wpilibc/src/test/native/cpp/TimerTest.cpp
new file mode 100644
index 0000000000..a7adc45b42
--- /dev/null
+++ b/wpilibc/src/test/native/cpp/TimerTest.cpp
@@ -0,0 +1,115 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "frc/Timer.h"  // NOLINT(build/include_order)
+
+#include "frc/simulation/SimHooks.h"
+#include "gtest/gtest.h"
+
+using namespace frc;
+
+namespace {
+class TimerTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    frc::sim::PauseTiming();
+    frc::sim::RestartTiming();
+  }
+
+  void TearDown() override { frc::sim::ResumeTiming(); }
+};
+
+}  // namespace
+
+TEST_F(TimerTest, StartStop) {
+  Timer timer;
+
+  // Verify timer is initialized as stopped
+  EXPECT_EQ(timer.Get(), 0_s);
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 0_s);
+
+  // Verify timer increments after it's started
+  timer.Start();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer stops incrementing after it's stopped
+  timer.Stop();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+}
+
+TEST_F(TimerTest, Reset) {
+  Timer timer;
+  timer.Start();
+
+  // Advance timer to 500 ms
+  EXPECT_EQ(timer.Get(), 0_s);
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer reports 0 ms after reset
+  timer.Reset();
+  EXPECT_EQ(timer.Get(), 0_s);
+
+  // Verify timer continues incrementing
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer doesn't start incrementing after reset if it was stopped
+  timer.Stop();
+  timer.Reset();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 0_ms);
+}
+
+TEST_F(TimerTest, HasElapsed) {
+  Timer timer;
+
+  // Verify 0 ms has elapsed since timer hasn't started
+  EXPECT_TRUE(timer.HasElapsed(0_s));
+
+  // Verify timer doesn't report elapsed time when stopped
+  frc::sim::StepTiming(500_ms);
+  EXPECT_FALSE(timer.HasElapsed(400_ms));
+
+  timer.Start();
+
+  // Verify timer reports >= 400 ms has elapsed after multiple calls
+  frc::sim::StepTiming(500_ms);
+  EXPECT_TRUE(timer.HasElapsed(400_ms));
+  EXPECT_TRUE(timer.HasElapsed(400_ms));
+}
+
+TEST_F(TimerTest, AdvanceIfElapsed) {
+  Timer timer;
+
+  // Verify 0 ms has elapsed since timer hasn't started
+  EXPECT_TRUE(timer.AdvanceIfElapsed(0_s));
+
+  // Verify timer doesn't report elapsed time when stopped
+  frc::sim::StepTiming(500_ms);
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+
+  timer.Start();
+
+  // Verify timer reports >= 400 ms has elapsed for only first call
+  frc::sim::StepTiming(500_ms);
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+
+  // Verify timer reports >= 400 ms has elapsed for two calls
+  frc::sim::StepTiming(1_s);
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+}
+
+TEST_F(TimerTest, GetFPGATimestamp) {
+  auto start = frc::Timer::GetFPGATimestamp();
+  frc::sim::StepTiming(500_ms);
+  auto end = frc::Timer::GetFPGATimestamp();
+  EXPECT_EQ(start + 500_ms, end);
+}
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
index 17e1164c38..cead2ce4d0 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/Timer.java
@@ -123,7 +123,7 @@ public class Timer {
    */
   public boolean hasElapsed(double seconds) {
     synchronized (m_lock) {
-      return get() > seconds;
+      return get() >= seconds;
     }
   }
 
@@ -151,7 +151,7 @@ public class Timer {
    */
   public boolean advanceIfElapsed(double seconds) {
     synchronized (m_lock) {
-      if (get() > seconds) {
+      if (get() >= seconds) {
         // Advance the start time by the period.
         // Don't set it to the current time... we want to avoid drift.
         m_startTime += seconds * 1000;
diff --git a/wpilibj/src/test/java/edu/wpi/first/wpilibj/TimerTest.java b/wpilibj/src/test/java/edu/wpi/first/wpilibj/TimerTest.java
new file mode 100644
index 0000000000..89619dd633
--- /dev/null
+++ b/wpilibj/src/test/java/edu/wpi/first/wpilibj/TimerTest.java
@@ -0,0 +1,132 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.wpilibj;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import edu.wpi.first.hal.HAL;
+import edu.wpi.first.wpilibj.simulation.SimHooks;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.ResourceLock;
+
+class TimerTest {
+  @BeforeEach
+  void setup() {
+    HAL.initialize(500, 0);
+    SimHooks.pauseTiming();
+    SimHooks.restartTiming();
+  }
+
+  @AfterEach
+  void cleanup() {
+    SimHooks.resumeTiming();
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void startStopTest() {
+    var timer = new Timer();
+
+    // Verify timer is initialized as stopped
+    assertEquals(timer.get(), 0.0);
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.0);
+
+    // Verify timer increments after it's started
+    timer.start();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer stops incrementing after it's stopped
+    timer.stop();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void resetTest() {
+    var timer = new Timer();
+    timer.start();
+
+    // Advance timer to 500 ms
+    assertEquals(timer.get(), 0.0);
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer reports 0 ms after reset
+    timer.reset();
+    assertEquals(timer.get(), 0.0);
+
+    // Verify timer continues incrementing
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer doesn't start incrementing after reset if it was stopped
+    timer.stop();
+    timer.reset();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.0);
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void hasElapsedTest() {
+    var timer = new Timer();
+
+    // Verify 0 ms has elapsed since timer hasn't started
+    assertTrue(timer.hasElapsed(0.0));
+
+    // Verify timer doesn't report elapsed time when stopped
+    SimHooks.stepTiming(0.5);
+    assertFalse(timer.hasElapsed(0.4));
+
+    timer.start();
+
+    // Verify timer reports >= 400 ms has elapsed after multiple calls
+    SimHooks.stepTiming(0.5);
+    assertTrue(timer.hasElapsed(0.4));
+    assertTrue(timer.hasElapsed(0.4));
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void advanceIfElapsedTest() {
+    var timer = new Timer();
+
+    // Verify 0 ms has elapsed since timer hasn't started
+    assertTrue(timer.advanceIfElapsed(0.0));
+
+    // Verify timer doesn't report elapsed time when stopped
+    SimHooks.stepTiming(0.5);
+    assertFalse(timer.advanceIfElapsed(0.4));
+
+    timer.start();
+
+    // Verify timer reports >= 400 ms has elapsed for only first call
+    SimHooks.stepTiming(0.5);
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertFalse(timer.advanceIfElapsed(0.4));
+
+    // Verify timer reports >= 400 ms has elapsed for two calls
+    SimHooks.stepTiming(1.0);
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertFalse(timer.advanceIfElapsed(0.4));
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void getFPGATimestampTest() {
+    double start = Timer.getFPGATimestamp();
+    SimHooks.stepTiming(0.5);
+    double end = Timer.getFPGATimestamp();
+    assertEquals(start + 0.5, end, 1e-9);
+  }
+}