diff --git a/tests/baselines/reference/requiredInitializedParameter1.errors.txt b/tests/baselines/reference/requiredInitializedParameter1.errors.txt
new file mode 100644
index 00000000000..ef958dbdec9
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter1.errors.txt
@@ -0,0 +1,28 @@
+tests/cases/compiler/requiredInitializedParameter1.ts(11,1): error TS2346: Supplied parameters do not match any signature of call target.
+tests/cases/compiler/requiredInitializedParameter1.ts(16,1): error TS2346: Supplied parameters do not match any signature of call target.
+
+
+==== tests/cases/compiler/requiredInitializedParameter1.ts (2 errors) ====
+    function f1(a, b = 0, c) { }
+    function f2(a, b = 0, c = 0) { }
+    function f3(a, b = 0, c?) { }
+    function f4(a, b = 0, ...c) { }
+    
+    f1(0, 1, 2);
+    f2(0, 1, 2);
+    f3(0, 1, 2);
+    f4(0, 1, 2);
+    
+    f1(0, 1);
+    ~~~~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    f2(0, 1);
+    f3(0, 1);
+    f4(0, 1);
+    
+    f1(0);
+    ~~~~~
+!!! error TS2346: Supplied parameters do not match any signature of call target.
+    f2(0);
+    f3(0);
+    f4(0);
\ No newline at end of file
diff --git a/tests/baselines/reference/requiredInitializedParameter1.js b/tests/baselines/reference/requiredInitializedParameter1.js
new file mode 100644
index 00000000000..0fe07503056
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter1.js
@@ -0,0 +1,51 @@
+//// [requiredInitializedParameter1.ts]
+function f1(a, b = 0, c) { }
+function f2(a, b = 0, c = 0) { }
+function f3(a, b = 0, c?) { }
+function f4(a, b = 0, ...c) { }
+
+f1(0, 1, 2);
+f2(0, 1, 2);
+f3(0, 1, 2);
+f4(0, 1, 2);
+
+f1(0, 1);
+f2(0, 1);
+f3(0, 1);
+f4(0, 1);
+
+f1(0);
+f2(0);
+f3(0);
+f4(0);
+
+//// [requiredInitializedParameter1.js]
+function f1(a, b, c) {
+    if (b === void 0) { b = 0; }
+}
+function f2(a, b, c) {
+    if (b === void 0) { b = 0; }
+    if (c === void 0) { c = 0; }
+}
+function f3(a, b, c) {
+    if (b === void 0) { b = 0; }
+}
+function f4(a, b) {
+    if (b === void 0) { b = 0; }
+    var c = [];
+    for (var _i = 2; _i < arguments.length; _i++) {
+        c[_i - 2] = arguments[_i];
+    }
+}
+f1(0, 1, 2);
+f2(0, 1, 2);
+f3(0, 1, 2);
+f4(0, 1, 2);
+f1(0, 1);
+f2(0, 1);
+f3(0, 1);
+f4(0, 1);
+f1(0);
+f2(0);
+f3(0);
+f4(0);
diff --git a/tests/baselines/reference/requiredInitializedParameter2.errors.txt b/tests/baselines/reference/requiredInitializedParameter2.errors.txt
new file mode 100644
index 00000000000..5dcec536e1b
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter2.errors.txt
@@ -0,0 +1,17 @@
+tests/cases/compiler/requiredInitializedParameter2.ts(5,7): error TS2420: Class 'C1' incorrectly implements interface 'I1'.
+  Types of property 'method' are incompatible.
+    Type '(a: number, b: any) => void' is not assignable to type '() => any'.
+
+
+==== tests/cases/compiler/requiredInitializedParameter2.ts (1 errors) ====
+    interface I1 {
+        method();
+    }
+    
+    class C1 implements I1 {
+          ~~
+!!! error TS2420: Class 'C1' incorrectly implements interface 'I1'.
+!!! error TS2420:   Types of property 'method' are incompatible.
+!!! error TS2420:     Type '(a: number, b: any) => void' is not assignable to type '() => any'.
+        method(a = 0, b) { }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/requiredInitializedParameter2.js b/tests/baselines/reference/requiredInitializedParameter2.js
new file mode 100644
index 00000000000..3c69d54e1d9
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter2.js
@@ -0,0 +1,18 @@
+//// [requiredInitializedParameter2.ts]
+interface I1 {
+    method();
+}
+
+class C1 implements I1 {
+    method(a = 0, b) { }
+}
+
+//// [requiredInitializedParameter2.js]
+var C1 = (function () {
+    function C1() {
+    }
+    C1.prototype.method = function (a, b) {
+        if (a === void 0) { a = 0; }
+    };
+    return C1;
+})();
diff --git a/tests/baselines/reference/requiredInitializedParameter3.js b/tests/baselines/reference/requiredInitializedParameter3.js
new file mode 100644
index 00000000000..68e1aa696ea
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter3.js
@@ -0,0 +1,27 @@
+//// [requiredInitializedParameter3.ts]
+interface I1 {
+    method();
+}
+
+class C1 implements I1 {
+    method(a = 0, b?) { }
+}
+
+//// [requiredInitializedParameter3.js]
+var C1 = (function () {
+    function C1() {
+    }
+    C1.prototype.method = function (a, b) {
+        if (a === void 0) { a = 0; }
+    };
+    return C1;
+})();
+
+
+//// [requiredInitializedParameter3.d.ts]
+interface I1 {
+    method(): any;
+}
+declare class C1 implements I1 {
+    method(a?: number, b?: any): void;
+}
diff --git a/tests/baselines/reference/requiredInitializedParameter3.symbols b/tests/baselines/reference/requiredInitializedParameter3.symbols
new file mode 100644
index 00000000000..e9f35b21bcf
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter3.symbols
@@ -0,0 +1,17 @@
+=== tests/cases/compiler/requiredInitializedParameter3.ts ===
+interface I1 {
+>I1 : Symbol(I1, Decl(requiredInitializedParameter3.ts, 0, 0))
+
+    method();
+>method : Symbol(method, Decl(requiredInitializedParameter3.ts, 0, 14))
+}
+
+class C1 implements I1 {
+>C1 : Symbol(C1, Decl(requiredInitializedParameter3.ts, 2, 1))
+>I1 : Symbol(I1, Decl(requiredInitializedParameter3.ts, 0, 0))
+
+    method(a = 0, b?) { }
+>method : Symbol(method, Decl(requiredInitializedParameter3.ts, 4, 24))
+>a : Symbol(a, Decl(requiredInitializedParameter3.ts, 5, 11))
+>b : Symbol(b, Decl(requiredInitializedParameter3.ts, 5, 17))
+}
diff --git a/tests/baselines/reference/requiredInitializedParameter3.types b/tests/baselines/reference/requiredInitializedParameter3.types
new file mode 100644
index 00000000000..aa37f5e13dd
--- /dev/null
+++ b/tests/baselines/reference/requiredInitializedParameter3.types
@@ -0,0 +1,18 @@
+=== tests/cases/compiler/requiredInitializedParameter3.ts ===
+interface I1 {
+>I1 : I1
+
+    method();
+>method : () => any
+}
+
+class C1 implements I1 {
+>C1 : C1
+>I1 : I1
+
+    method(a = 0, b?) { }
+>method : (a?: number, b?: any) => void
+>a : number
+>0 : number
+>b : any
+}
diff --git a/tests/cases/compiler/requiredInitializedParameter1.ts b/tests/cases/compiler/requiredInitializedParameter1.ts
new file mode 100644
index 00000000000..35d606426f0
--- /dev/null
+++ b/tests/cases/compiler/requiredInitializedParameter1.ts
@@ -0,0 +1,19 @@
+function f1(a, b = 0, c) { }
+function f2(a, b = 0, c = 0) { }
+function f3(a, b = 0, c?) { }
+function f4(a, b = 0, ...c) { }
+
+f1(0, 1, 2);
+f2(0, 1, 2);
+f3(0, 1, 2);
+f4(0, 1, 2);
+
+f1(0, 1);
+f2(0, 1);
+f3(0, 1);
+f4(0, 1);
+
+f1(0);
+f2(0);
+f3(0);
+f4(0);
\ No newline at end of file
diff --git a/tests/cases/compiler/requiredInitializedParameter2.ts b/tests/cases/compiler/requiredInitializedParameter2.ts
new file mode 100644
index 00000000000..48d42869ee7
--- /dev/null
+++ b/tests/cases/compiler/requiredInitializedParameter2.ts
@@ -0,0 +1,7 @@
+interface I1 {
+    method();
+}
+
+class C1 implements I1 {
+    method(a = 0, b) { }
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/requiredInitializedParameter3.ts b/tests/cases/compiler/requiredInitializedParameter3.ts
new file mode 100644
index 00000000000..803eefb6342
--- /dev/null
+++ b/tests/cases/compiler/requiredInitializedParameter3.ts
@@ -0,0 +1,8 @@
+//@declaration: true
+interface I1 {
+    method();
+}
+
+class C1 implements I1 {
+    method(a = 0, b?) { }
+}
\ No newline at end of file