diff --git a/web3.js/module.flow.js b/web3.js/module.flow.js
index 9128b6ce36..9a300d5dee 100644
--- a/web3.js/module.flow.js
+++ b/web3.js/module.flow.js
@@ -124,13 +124,13 @@ declare module '@solana/web3.js' {
   declare export type TransactionSignature = string;
 
   declare type TransactionInstructionCtorFields = {|
-    keys: ?Array<{pubkey: PublicKey, isSigner: boolean}>,
+    keys: ?Array<{pubkey: PublicKey, isSigner: boolean, isDebitable: boolean}>,
     programId?: PublicKey,
     data?: Buffer,
   |};
 
   declare export class TransactionInstruction {
-    keys: Array<{pubkey: PublicKey, isSigner: boolean}>;
+    keys: Array<{pubkey: PublicKey, isSigner: boolean, isDebitable: boolean}>;
     programId: PublicKey;
     data: Buffer;
   }
diff --git a/web3.js/src/budget-program.js b/web3.js/src/budget-program.js
index e869f71c16..7e24b5f288 100644
--- a/web3.js/src/budget-program.js
+++ b/web3.js/src/budget-program.js
@@ -201,7 +201,10 @@ export class BudgetProgram {
         }
 
         return new Transaction().add({
-          keys: [{pubkey: from, isSigner: true}, {pubkey: to, isSigner: false}],
+          keys: [
+            {pubkey: from, isSigner: true, isDebitable: true},
+            {pubkey: to, isSigner: false, isDebitable: false},
+          ],
           programId: this.programId,
           data: data.slice(0, pos),
         });
@@ -222,9 +225,9 @@ export class BudgetProgram {
 
         return new Transaction().add({
           keys: [
-            {pubkey: from, isSigner: true},
-            {pubkey: program, isSigner: false},
-            {pubkey: to, isSigner: false},
+            {pubkey: from, isSigner: true, isDebitable: true},
+            {pubkey: program, isSigner: false, isDebitable: true},
+            {pubkey: to, isSigner: false, isDebitable: false},
           ],
           programId: this.programId,
           data: data.slice(0, pos),
@@ -246,9 +249,9 @@ export class BudgetProgram {
 
         return new Transaction().add({
           keys: [
-            {pubkey: from, isSigner: true},
-            {pubkey: program, isSigner: false},
-            {pubkey: to, isSigner: false},
+            {pubkey: from, isSigner: true, isDebitable: true},
+            {pubkey: program, isSigner: false, isDebitable: true},
+            {pubkey: to, isSigner: false, isDebitable: false},
           ],
           programId: this.programId,
           data: data.slice(0, pos),
@@ -294,9 +297,9 @@ export class BudgetProgram {
 
     return new Transaction().add({
       keys: [
-        {pubkey: from, isSigner: true},
-        {pubkey: program, isSigner: false},
-        {pubkey: to, isSigner: false},
+        {pubkey: from, isSigner: true, isDebitable: true},
+        {pubkey: program, isSigner: false, isDebitable: true},
+        {pubkey: to, isSigner: false, isDebitable: false},
       ],
       programId: this.programId,
       data: data.slice(0, pos),
@@ -321,9 +324,9 @@ export class BudgetProgram {
 
     return new Transaction().add({
       keys: [
-        {pubkey: from, isSigner: true},
-        {pubkey: program, isSigner: false},
-        {pubkey: to, isSigner: false},
+        {pubkey: from, isSigner: true, isDebitable: true},
+        {pubkey: program, isSigner: false, isDebitable: true},
+        {pubkey: to, isSigner: false, isDebitable: false},
       ],
       programId: this.programId,
       data,
@@ -351,9 +354,9 @@ export class BudgetProgram {
 
     return new Transaction().add({
       keys: [
-        {pubkey: from, isSigner: true},
-        {pubkey: program, isSigner: false},
-        {pubkey: to, isSigner: false},
+        {pubkey: from, isSigner: true, isDebitable: true},
+        {pubkey: program, isSigner: false, isDebitable: true},
+        {pubkey: to, isSigner: false, isDebitable: false},
       ],
       programId: this.programId,
       data,
diff --git a/web3.js/src/loader.js b/web3.js/src/loader.js
index c482d26ef3..4eb61b7bab 100644
--- a/web3.js/src/loader.js
+++ b/web3.js/src/loader.js
@@ -78,7 +78,7 @@ export class Loader {
       );
 
       const transaction = new Transaction().add({
-        keys: [{pubkey: program.publicKey, isSigner: true}],
+        keys: [{pubkey: program.publicKey, isSigner: true, isDebitable: true}],
         programId,
         data,
       });
@@ -117,7 +117,7 @@ export class Loader {
       );
 
       const transaction = new Transaction().add({
-        keys: [{pubkey: program.publicKey, isSigner: true}],
+        keys: [{pubkey: program.publicKey, isSigner: true, isDebitable: true}],
         programId,
         data,
       });
diff --git a/web3.js/src/system-program.js b/web3.js/src/system-program.js
index 91c27107a4..5ac67ff63c 100644
--- a/web3.js/src/system-program.js
+++ b/web3.js/src/system-program.js
@@ -49,8 +49,8 @@ export class SystemProgram {
 
     return new Transaction().add({
       keys: [
-        {pubkey: from, isSigner: true},
-        {pubkey: newAccount, isSigner: false},
+        {pubkey: from, isSigner: true, isDebitable: true},
+        {pubkey: newAccount, isSigner: false, isDebitable: true},
       ],
       programId: SystemProgram.programId,
       data,
@@ -76,7 +76,10 @@ export class SystemProgram {
     );
 
     return new Transaction().add({
-      keys: [{pubkey: from, isSigner: true}, {pubkey: to, isSigner: false}],
+      keys: [
+        {pubkey: from, isSigner: true, isDebitable: true},
+        {pubkey: to, isSigner: false, isDebitable: false},
+      ],
       programId: SystemProgram.programId,
       data,
     });
@@ -101,7 +104,7 @@ export class SystemProgram {
     );
 
     return new Transaction().add({
-      keys: [{pubkey: from, isSigner: true}],
+      keys: [{pubkey: from, isSigner: true, isDebitable: true}],
       programId: SystemProgram.programId,
       data,
     });
diff --git a/web3.js/src/token-program.js b/web3.js/src/token-program.js
index d0f7a7fddb..1244db7364 100644
--- a/web3.js/src/token-program.js
+++ b/web3.js/src/token-program.js
@@ -237,8 +237,8 @@ export class Token {
 
     transaction = new Transaction().add({
       keys: [
-        {pubkey: tokenAccount.publicKey, isSigner: true},
-        {pubkey: initialAccountPublicKey, isSigner: false},
+        {pubkey: tokenAccount.publicKey, isSigner: true, isDebitable: false},
+        {pubkey: initialAccountPublicKey, isSigner: false, isDebitable: true},
       ],
       programId,
       data,
@@ -292,12 +292,12 @@ export class Token {
 
     // Initialize the token account
     const keys = [
-      {pubkey: tokenAccount.publicKey, isSigner: true},
-      {pubkey: owner.publicKey, isSigner: false},
-      {pubkey: this.token, isSigner: false},
+      {pubkey: tokenAccount.publicKey, isSigner: true, isDebitable: true},
+      {pubkey: owner.publicKey, isSigner: false, isDebitable: false},
+      {pubkey: this.token, isSigner: false, isDebitable: false},
     ];
     if (source) {
-      keys.push({pubkey: source, isSigner: false});
+      keys.push({pubkey: source, isSigner: false, isDebitable: false});
     }
     transaction = new Transaction().add({
       keys,
@@ -496,12 +496,16 @@ export class Token {
     );
 
     const keys = [
-      {pubkey: owner, isSigner: true},
-      {pubkey: source, isSigner: false},
-      {pubkey: destination, isSigner: false},
+      {pubkey: owner, isSigner: true, isDebitable: false},
+      {pubkey: source, isSigner: false, isDebitable: true},
+      {pubkey: destination, isSigner: false, isDebitable: true},
     ];
     if (accountInfo.source) {
-      keys.push({pubkey: accountInfo.source, isSigner: false});
+      keys.push({
+        pubkey: accountInfo.source,
+        isSigner: false,
+        isDebitable: true,
+      });
     }
     return new TransactionInstruction({
       keys,
@@ -540,9 +544,9 @@ export class Token {
 
     return new TransactionInstruction({
       keys: [
-        {pubkey: owner, isSigner: true},
-        {pubkey: account, isSigner: false},
-        {pubkey: delegate, isSigner: false},
+        {pubkey: owner, isSigner: true, isDebitable: false},
+        {pubkey: account, isSigner: false, isDebitable: true},
+        {pubkey: delegate, isSigner: false, isDebitable: true},
       ],
       programId: this.programId,
       data,
@@ -588,9 +592,9 @@ export class Token {
 
     return new TransactionInstruction({
       keys: [
-        {pubkey: owner, isSigner: true},
-        {pubkey: account, isSigner: false},
-        {pubkey: newOwner, isSigner: false},
+        {pubkey: owner, isSigner: true, isDebitable: false},
+        {pubkey: account, isSigner: false, isDebitable: true},
+        {pubkey: newOwner, isSigner: false, isDebitable: true},
       ],
       programId: this.programId,
       data,
diff --git a/web3.js/src/transaction.js b/web3.js/src/transaction.js
index 081ca78ba8..444dafaf6e 100644
--- a/web3.js/src/transaction.js
+++ b/web3.js/src/transaction.js
@@ -30,7 +30,7 @@ export const PACKET_DATA_SIZE = 512;
  * @property {?Buffer} data
  */
 type TransactionInstructionCtorFields = {|
-  keys?: Array<{pubkey: PublicKey, isSigner: boolean}>,
+  keys?: Array<{pubkey: PublicKey, isSigner: boolean, isDebitable: boolean}>,
   programId?: PublicKey,
   data?: Buffer,
 |};
@@ -43,7 +43,11 @@ export class TransactionInstruction {
    * Public keys to include in this transaction
    * Boolean represents whether this pubkey needs to sign the transaction
    */
-  keys: Array<{pubkey: PublicKey, isSigner: boolean}> = [];
+  keys: Array<{
+    pubkey: PublicKey,
+    isSigner: boolean,
+    isDebitable: boolean,
+  }> = [];
 
   /**
    * Program Id to execute
@@ -166,6 +170,13 @@ export class Transaction {
         if (!keys.includes(keyStr)) {
           if (keySignerPair.isSigner) {
             numRequiredSignatures += 1;
+            if (!keySignerPair.isDebitable) {
+              numCreditOnlySignedAccounts += 1;
+            }
+          } else {
+            if (!keySignerPair.isDebitable) {
+              numCreditOnlyUnsignedAccounts += 1;
+            }
           }
           keys.push(keyStr);
         }
@@ -422,6 +433,20 @@ export class Transaction {
     const PUBKEY_LENGTH = 32;
     const SIGNATURE_LENGTH = 64;
 
+    function isCreditDebit(
+      i: number,
+      numRequiredSignatures: number,
+      numCreditOnlySignedAccounts: number,
+      numCreditOnlyUnsignedAccounts: number,
+      numKeys: number,
+    ): boolean {
+      return (
+        i < numRequiredSignatures - numCreditOnlySignedAccounts ||
+        (i >= numRequiredSignatures &&
+          i < numKeys - numCreditOnlyUnsignedAccounts)
+      );
+    }
+
     let transaction = new Transaction();
 
     // Slice up wire data
@@ -435,9 +460,12 @@ export class Transaction {
       signatures.push(signature);
     }
 
-    byteArray = byteArray.slice(1); // Skip numRequiredSignatures byte
-    byteArray = byteArray.slice(1); // Skip numCreditOnlySignedAccounts byte
-    byteArray = byteArray.slice(1); // Skip numCreditOnlyUnsignedAccounts byte
+    const numRequiredSignatures = byteArray.shift();
+    // byteArray = byteArray.slice(1); // Skip numRequiredSignatures byte
+    const numCreditOnlySignedAccounts = byteArray.shift();
+    // byteArray = byteArray.slice(1); // Skip numCreditOnlySignedAccounts byte
+    const numCreditOnlyUnsignedAccounts = byteArray.shift();
+    // byteArray = byteArray.slice(1); // Skip numCreditOnlyUnsignedAccounts byte
 
     const accountCount = shortvec.decodeLength(byteArray);
     let accounts = [];
@@ -481,11 +509,19 @@ export class Transaction {
       };
       for (let j = 0; j < instructions[i].accountIndex.length; j++) {
         const pubkey = new PublicKey(accounts[instructions[i].accountIndex[j]]);
+
         instructionData.keys.push({
           pubkey,
           isSigner: transaction.signatures.some(
             keyObj => keyObj.publicKey.toString() === pubkey.toString(),
           ),
+          isDebitable: isCreditDebit(
+            j,
+            numRequiredSignatures,
+            numCreditOnlySignedAccounts,
+            numCreditOnlyUnsignedAccounts,
+            accounts.length,
+          ),
         });
       }
       let instruction = new TransactionInstruction(instructionData);
diff --git a/web3.js/test/bpf-loader.test.js b/web3.js/test/bpf-loader.test.js
index a6d120bffb..257bfdbe14 100644
--- a/web3.js/test/bpf-loader.test.js
+++ b/web3.js/test/bpf-loader.test.js
@@ -28,7 +28,7 @@ test('load BPF C program', async () => {
   const data = await fs.readFile('test/fixtures/noop-c/noop.so');
   const programId = await BpfLoader.load(connection, from, data);
   const transaction = new Transaction().add({
-    keys: [{pubkey: from.publicKey, isSigner: true}],
+    keys: [{pubkey: from.publicKey, isSigner: true, isDebitable: true}],
     programId,
   });
   await sendAndConfirmTransaction(connection, transaction, from);
@@ -47,7 +47,7 @@ test('load BPF Rust program', async () => {
   );
   const programId = await BpfLoader.load(connection, from, data);
   const transaction = new Transaction().add({
-    keys: [{pubkey: from.publicKey, isSigner: true}],
+    keys: [{pubkey: from.publicKey, isSigner: true, isDebitable: true}],
     programId,
   });
   await sendAndConfirmTransaction(connection, transaction, from);
diff --git a/web3.js/test/native-loader.test.js b/web3.js/test/native-loader.test.js
index 9f092bca12..b8fb5362e6 100644
--- a/web3.js/test/native-loader.test.js
+++ b/web3.js/test/native-loader.test.js
@@ -29,7 +29,7 @@ test('load native program', async () => {
     'solana_noop_program',
   );
   const transaction = new Transaction().add({
-    keys: [{pubkey: from.publicKey, isSigner: true}],
+    keys: [{pubkey: from.publicKey, isSigner: true, isDebitable: true}],
     programId,
   });
 
diff --git a/web3.js/test/transaction.test.js b/web3.js/test/transaction.test.js
index e9ac56bd2f..f63210960d 100644
--- a/web3.js/test/transaction.test.js
+++ b/web3.js/test/transaction.test.js
@@ -93,73 +93,73 @@ test('parse wire format and serialize', () => {
 
   const wireTransaction = Buffer.from([
     1,
-    91,
-    132,
-    173,
-    1,
-    218,
-    94,
-    253,
-    18,
-    27,
-    79,
-    207,
-    114,
-    27,
-    167,
-    127,
+    47,
+    50,
+    66,
     17,
-    202,
-    183,
-    204,
-    12,
-    69,
-    243,
-    25,
-    206,
-    165,
-    116,
-    182,
-    64,
-    185,
-    168,
-    238,
-    168,
-    193,
-    140,
-    86,
-    83,
-    107,
-    252,
-    239,
-    80,
+    219,
+    90,
+    187,
+    49,
     40,
-    91,
-    44,
-    6,
-    160,
-    84,
-    43,
-    227,
-    63,
-    170,
-    255,
-    185,
-    132,
-    242,
-    82,
-    46,
-    124,
-    217,
-    127,
-    147,
-    24,
-    254,
-    157,
+    77,
+    8,
+    58,
+    129,
+    51,
+    76,
     13,
+    206,
+    126,
+    157,
+    189,
+    188,
+    53,
+    174,
+    42,
+    80,
+    4,
+    4,
+    212,
+    55,
+    67,
+    171,
+    34,
+    224,
+    81,
+    68,
+    230,
+    120,
+    117,
+    204,
+    241,
+    167,
+    152,
+    74,
+    141,
+    132,
+    73,
+    166,
+    217,
+    173,
+    27,
+    75,
+    62,
+    171,
+    160,
+    100,
+    159,
+    116,
+    164,
+    45,
+    185,
+    64,
+    0,
+    72,
+    4,
     1,
     0,
-    1,
+    2,
     3,
     19,
     152,