@@ -268,6 +268,10 @@ err = tcc.FillBlocksExtra(blocksData, &tilCfgExtra)
 	if err != nil {
 		panic(err)
 	}
+	err = tcc.FillBlocksForgedL1UserTxs(blocksData)
+	if err != nil {
+		panic(err)
+	}
 	AddAditionalInformation(blocksData)
 	// Generate L2 Txs with til
 	commonPoolTxs, err := tcc.GeneratePoolL2Txs(txsets.SetPoolL2MinimumFlow0)
@@ -330,7 +334,6 @@ }
 			testTokens = append(testTokens, token)
 		}
 		// Set USD value for tokens in DB
-		commonL1Txs = append(commonL1Txs, block.Rollup.L1UserTxs...)
 		for _, batch := range block.Rollup.Batches {
 			commonL2Txs = append(commonL2Txs, batch.L2Txs...)
 			for i := range batch.CreatedAccounts {
@@ -339,6 +342,7 @@ commonAccounts = append(commonAccounts, batch.CreatedAccounts[i])
 			}
 			commonBatches = append(commonBatches, batch.Batch)
 			commonExitTree = append(commonExitTree, batch.ExitTree...)
+			commonL1Txs = append(commonL1Txs, batch.L1UserTxs...)
 			commonL1Txs = append(commonL1Txs, batch.L1CoordinatorTxs...)
 		}
 	}

@@ -143,14 +143,9 @@ // WARNING: this is an asumption, and the test input data can brake it easily
 			bn := common.BatchNum(*tx.L1Info.ToForgeL1TxsNum + 2)
 			tx.BatchNum = &bn
 		}
-		// TODO: User L1 txs that create txs will have fromAccountIndex equal to the idx of the
-		// created account. Once this is done this test will be broken and will need to be updated here.
-		// At the moment they are null
-		if l1.Type != common.TxTypeCreateAccountDeposit &&
-			l1.Type != common.TxTypeCreateAccountDepositTransfer {
-			idxStr := idxToHez(l1.FromIdx, token.Symbol)
-			tx.FromIdx = &idxStr
-		}
+		// If FromIdx is not nil
+		idxStr := idxToHez(l1.EffectiveFromIdx, token.Symbol)
+		tx.FromIdx = &idxStr
 		// If tx has a normal ToIdx (>255), set FromEthAddr and FromBJJ
 		if l1.ToIdx >= common.UserThreshold {
 			// find account

@@ -28,16 +28,17 @@ // values: | type | ToForgeL1TxsNum | Position | 0 (padding) |
 	// where type:
 	// 	- L1UserTx: 0
 	// 	- L1CoordinatorTx: 1
-	TxID            TxID                  `meddler:"id"`
-	ToForgeL1TxsNum *int64                `meddler:"to_forge_l1_txs_num"` // toForgeL1TxsNum in which the tx was forged / will be forged
-	Position        int                   `meddler:"position"`
-	UserOrigin      bool                  `meddler:"user_origin"`         // true if the tx was originated by a user, false if it was aoriginated by a coordinator. Note that this differ from the spec for implementation simplification purpposes
-	FromIdx         Idx                   `meddler:"from_idx,zeroisnull"` // FromIdx is used by L1Tx/Deposit to indicate the Idx receiver of the L1Tx.DepositAmount (deposit)
-	FromEthAddr     ethCommon.Address     `meddler:"from_eth_addr,zeroisnull"`
-	FromBJJ         babyjub.PublicKeyComp `meddler:"from_bjj,zeroisnull"`
-	ToIdx           Idx                   `meddler:"to_idx"` // ToIdx is ignored in L1Tx/Deposit, but used in the L1Tx/DepositAndTransfer
-	TokenID         TokenID               `meddler:"token_id"`
-	Amount          *big.Int              `meddler:"amount,bigint"`
+	TxID             TxID                  `meddler:"id"`
+	ToForgeL1TxsNum  *int64                `meddler:"to_forge_l1_txs_num"` // toForgeL1TxsNum in which the tx was forged / will be forged
+	Position         int                   `meddler:"position"`
+	UserOrigin       bool                  `meddler:"user_origin"`         // true if the tx was originated by a user, false if it was aoriginated by a coordinator. Note that this differ from the spec for implementation simplification purpposes
+	FromIdx          Idx                   `meddler:"from_idx,zeroisnull"` // FromIdx is used by L1Tx/Deposit to indicate the Idx receiver of the L1Tx.DepositAmount (deposit)
+	EffectiveFromIdx Idx                   `meddler:"effective_from_idx,zeroisnull"`
+	FromEthAddr      ethCommon.Address     `meddler:"from_eth_addr,zeroisnull"`
+	FromBJJ          babyjub.PublicKeyComp `meddler:"from_bjj,zeroisnull"`
+	ToIdx            Idx                   `meddler:"to_idx"` // ToIdx is ignored in L1Tx/Deposit, but used in the L1Tx/DepositAndTransfer
+	TokenID          TokenID               `meddler:"token_id"`
+	Amount           *big.Int              `meddler:"amount,bigint"`
 	// EffectiveAmount only applies to L1UserTx.
 	EffectiveAmount *big.Int `meddler:"effective_amount,bigintnull"`
 	DepositAmount   *big.Int `meddler:"deposit_amount,bigint"`

@@ -852,9 +852,13 @@ amountFloat, _ := af.Float64()
 		laf := new(big.Float).SetInt(l1txs[i].DepositAmount)
 		depositAmountFloat, _ := laf.Float64()
 		var effectiveFromIdx *common.Idx
-		if l1txs[i].Type != common.TxTypeCreateAccountDeposit &&
-			l1txs[i].Type != common.TxTypeCreateAccountDepositTransfer {
-			effectiveFromIdx = &l1txs[i].FromIdx
+		if l1txs[i].UserOrigin {
+			if l1txs[i].Type != common.TxTypeCreateAccountDeposit &&
+				l1txs[i].Type != common.TxTypeCreateAccountDepositTransfer {
+				effectiveFromIdx = &l1txs[i].FromIdx
+			}
+		} else {
+			effectiveFromIdx = &l1txs[i].EffectiveFromIdx
 		}
 		txs = append(txs, txWrite{
 			// Generic
@@ -1242,7 +1246,7 @@ var txs []*common.L1Tx
 	err := meddler.QueryAll(
 		hdb.db, &txs, // Note that '\x' gets parsed as a big.Int with value = 0
 		`SELECT tx.id, tx.to_forge_l1_txs_num, tx.position, tx.user_origin,
-		tx.from_idx, tx.from_eth_addr, tx.from_bjj, tx.to_idx, tx.token_id,
+		tx.from_idx, tx.effective_from_idx, tx.from_eth_addr, tx.from_bjj, tx.to_idx, tx.token_id,
 		tx.amount, (CASE WHEN tx.batch_num IS NULL THEN NULL WHEN tx.amount_success THEN tx.amount ELSE '\x' END) AS effective_amount,
 		tx.deposit_amount, (CASE WHEN tx.batch_num IS NULL THEN NULL WHEN tx.deposit_amount_success THEN tx.deposit_amount ELSE '\x' END) AS effective_deposit_amount,
 		tx.eth_block_num, tx.type, tx.batch_num
@@ -1259,7 +1263,7 @@ // that returned txs will always have effective amounts
 	err := meddler.QueryAll(
 		hdb.db, &txs,
 		`SELECT tx.id, tx.to_forge_l1_txs_num, tx.position, tx.user_origin,
-		tx.from_idx, tx.from_eth_addr, tx.from_bjj, tx.to_idx, tx.token_id,
+		tx.from_idx, tx.effective_from_idx, tx.from_eth_addr, tx.from_bjj, tx.to_idx, tx.token_id,
 		tx.amount, tx.amount AS effective_amount,
 		tx.deposit_amount, tx.deposit_amount AS effective_deposit_amount,
 		tx.eth_block_num, tx.type, tx.batch_num
@@ -1477,20 +1481,21 @@
 	return tracerr.Wrap(txn.Commit())
 }
 
-// setExtraInfoForgedL1UserTxs sets the EffectiveAmount and EffectiveDepositAmount
-// of the given l1UserTxs (with an UPDATE)
-// TODO: Set effective_from_idx for txs that create accounts
+// setExtraInfoForgedL1UserTxs sets the EffectiveAmount, EffectiveDepositAmount
+// and EffectiveFromIdx of the given l1UserTxs (with an UPDATE)
 func (hdb *HistoryDB) setExtraInfoForgedL1UserTxs(d sqlx.Ext, txs []common.L1Tx) error {
 	if len(txs) == 0 {
 		return nil
 	}
 	// Effective amounts are stored as success flags in the DB, with true value by default
 	// to reduce the amount of updates. Therefore, only amounts that became uneffective should be
-	// updated to become false
+	// updated to become false.  At the same time, all the txs that contain
+	// accounts (FromIdx == 0) are updated to set the EffectiveFromIdx.
 	type txUpdate struct {
 		ID                   common.TxID `db:"id"`
 		AmountSuccess        bool        `db:"amount_success"`
 		DepositAmountSuccess bool        `db:"deposit_amount_success"`
+		EffectiveFromIdx     common.Idx  `db:"effective_from_idx"`
 	}
 	txUpdates := []txUpdate{}
 	equal := func(a *big.Int, b *big.Int) bool {
@@ -1499,22 +1504,24 @@ }
 	for i := range txs {
 		amountSuccess := equal(txs[i].Amount, txs[i].EffectiveAmount)
 		depositAmountSuccess := equal(txs[i].DepositAmount, txs[i].EffectiveDepositAmount)
-		if !amountSuccess || !depositAmountSuccess {
+		if !amountSuccess || !depositAmountSuccess || txs[i].FromIdx == 0 {
 			txUpdates = append(txUpdates, txUpdate{
 				ID:                   txs[i].TxID,
 				AmountSuccess:        amountSuccess,
 				DepositAmountSuccess: depositAmountSuccess,
+				EffectiveFromIdx:     txs[i].EffectiveFromIdx,
 			})
 		}
 	}
 	const query string = `
 		UPDATE tx SET
 			amount_success = tx_update.amount_success,
-			deposit_amount_success = tx_update.deposit_amount_success
+			deposit_amount_success = tx_update.deposit_amount_success,
+			effective_from_idx = tx_update.effective_from_idx
 		FROM (VALUES
-			(NULL::::BYTEA, NULL::::BOOL, NULL::::BOOL),
-			(:id, :amount_success, :deposit_amount_success)
-		) as tx_update (id, amount_success, deposit_amount_success)
+			(NULL::::BYTEA, NULL::::BOOL, NULL::::BOOL, NULL::::BIGINT),
+			(:id, :amount_success, :deposit_amount_success, :effective_from_idx)
+		) as tx_update (id, amount_success, deposit_amount_success, effective_from_idx)
 		WHERE tx.id = tx_update.id;
 	`
 	if len(txUpdates) > 0 {
@@ -1604,7 +1611,6 @@ }
 
 		// Set the EffectiveAmount and EffectiveDepositAmount of all the
 		// L1UserTxs that have been forged in this batch
-		// TODO: Set also effective_from_idx for txs that create accounts
 		if err = hdb.setExtraInfoForgedL1UserTxs(txn, batch.L1UserTxs); err != nil {
 			return tracerr.Wrap(err)
 		}

@@ -791,9 +791,10 @@ }
 	// Add second batch to trigger the update of the batch_num,
 	// while avoiding the implicit call of setExtraInfoForgedL1UserTxs
 	err = historyDB.addBlock(historyDB.db, &blocks[1].Block)
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	err = historyDB.addBatch(historyDB.db, &blocks[1].Rollup.Batches[0].Batch)
-	assert.NoError(t, err)
+	require.NoError(t, err)
+	err = historyDB.addAccounts(historyDB.db, blocks[1].Rollup.Batches[0].CreatedAccounts)
 	require.NoError(t, err)
 
 	// Set the Effective{Amount,DepositAmount} of the L1UserTxs that are forged in the second block

@@ -172,6 +172,7 @@ }
 
 	sync, err := synchronizer.NewSynchronizer(client, historyDB, stateDB, synchronizer.Config{
 		StatsRefreshPeriod: cfg.Synchronizer.StatsRefreshPeriod.Duration,
+		ChainID:            chainIDU16,
 	})
 	if err != nil {
 		return nil, tracerr.Wrap(err)

@@ -180,6 +180,7 @@
 // Config is the Synchronizer configuration
 type Config struct {
 	StatsRefreshPeriod time.Duration
+	ChainID            uint16
 }
 
 // Synchronizer implements the Synchronizer type
@@ -797,17 +798,21 @@
 		// Transform L2 txs to PoolL2Txs
 		poolL2Txs := common.L2TxsToPoolL2Txs(forgeBatchArgs.L2TxsData) // NOTE: This is a big ugly, find a better way
 
-		// ProcessTxs updates poolL2Txs adding: Nonce (and also TokenID, but we don't use it).
-		//nolint:gomnd
-		tpc := txprocessor.Config{ // TODO TMP
-			NLevels:  32,
-			MaxFeeTx: 64,
-			MaxTx:    512,
-			MaxL1Tx:  64,
-			ChainID:  uint16(0),
+		if int(forgeBatchArgs.VerifierIdx) >= len(s.consts.Rollup.Verifiers) {
+			return nil, tracerr.Wrap(fmt.Errorf("forgeBatchArgs.VerifierIdx (%v) >= "+
+				" len(s.consts.Rollup.Verifiers) (%v)",
+				forgeBatchArgs.VerifierIdx, len(s.consts.Rollup.Verifiers)))
+		}
+		tpc := txprocessor.Config{
+			NLevels:  uint32(s.consts.Rollup.Verifiers[forgeBatchArgs.VerifierIdx].NLevels),
+			MaxTx:    uint32(s.consts.Rollup.Verifiers[forgeBatchArgs.VerifierIdx].MaxTx),
+			ChainID:  s.cfg.ChainID,
+			MaxFeeTx: common.RollupConstMaxFeeIdxCoordinator,
+			MaxL1Tx:  common.RollupConstMaxL1Tx,
 		}
 		tp := txprocessor.NewTxProcessor(s.stateDB, tpc)
 
+		// ProcessTxs updates poolL2Txs adding: Nonce (and also TokenID, but we don't use it).
 		processTxsOut, err := tp.ProcessTxs(forgeBatchArgs.FeeIdxCoordinator,
 			l1UserTxs, batchData.L1CoordinatorTxs, poolL2Txs)
 		if err != nil {

@@ -98,6 +98,11 @@ if *tx.ToForgeL1TxsNum == *_dbTx.ToForgeL1TxsNum &&
 				tx.Position == _dbTx.Position {
 				dbTx = new(common.L1Tx)
 				*dbTx = _dbTx
+				// NOTE: Overwrite EffectiveFromIdx in L1UserTx
+				// from db because we don't expect
+				// EffectiveFromIdx to be set yet, as this tx
+				// is not in yet forged
+				dbTx.EffectiveFromIdx = 0
 				break
 			}
 		}
@@ -142,7 +147,18 @@ assert.Equal(t, batch.CreatedAccounts, syncBatch.CreatedAccounts)
 		batch.Batch.NumAccounts = len(batch.CreatedAccounts)
 
 		// Test field by field to facilitate debugging of errors
+		assert.Equal(t, len(batch.L1UserTxs), len(syncBatch.L1UserTxs))
+		// NOTE: EffectiveFromIdx is set to til L1UserTxs in
+		// `FillBlocksForgedL1UserTxs` function
+		for j := range syncBatch.L1UserTxs {
+			assert.NotEqual(t, 0, syncBatch.L1UserTxs[j].EffectiveFromIdx)
+		}
 		assert.Equal(t, batch.L1UserTxs, syncBatch.L1UserTxs)
+		// NOTE: EffectiveFromIdx is set to til L1CoordinatorTxs in
+		// `FillBlocksExtra` function
+		for j := range syncBatch.L1CoordinatorTxs {
+			assert.NotEqual(t, 0, syncBatch.L1CoordinatorTxs[j].EffectiveFromIdx)
+		}
 		assert.Equal(t, batch.L1CoordinatorTxs, syncBatch.L1CoordinatorTxs)
 		assert.Equal(t, batch.L2Txs, syncBatch.L2Txs)
 		// In exit tree, we only check AccountIdx and Balance, because

@@ -45,6 +45,7 @@ openToForge     int64
 	toForgeL1TxsNum int64
 	nonces          map[common.Idx]common.Nonce
 	idx             int
+	idxByTxID       map[common.TxID]common.Idx
 }
 
 // Context contains the data of the test
@@ -107,6 +108,7 @@ openToForge:     0,
 			toForgeL1TxsNum: 0,
 			nonces:          make(map[common.Idx]common.Nonce),
 			idx:             common.UserThreshold,
+			idxByTxID:       make(map[common.TxID]common.Idx),
 		},
 	}
 }
@@ -762,7 +764,12 @@ }
 
 // FillBlocksForgedL1UserTxs fills the L1UserTxs of a batch with the L1UserTxs
 // that are forged in that batch.  It always sets `EffectiveAmount` = `Amount`
-// and `EffectiveDepositAmount` = `DepositAmount`.
+// and `EffectiveDepositAmount` = `DepositAmount`.  This function requires a
+// previous call to `FillBlocksExtra`.
+// - blocks[].Rollup.L1UserTxs[].BatchNum
+// - blocks[].Rollup.L1UserTxs[].EffectiveAmount
+// - blocks[].Rollup.L1UserTxs[].EffectiveDepositAmount
+// - blocks[].Rollup.L1UserTxs[].EffectiveFromIdx
 func (tc *Context) FillBlocksForgedL1UserTxs(blocks []common.BlockData) error {
 	for i := range blocks {
 		block := &blocks[i]
@@ -783,6 +790,11 @@ if err != nil {
 						return tracerr.Wrap(err)
 					}
 					*tx = *_tx
+					if tx.FromIdx == 0 {
+						tx.EffectiveFromIdx = tc.extra.idxByTxID[tx.TxID]
+					} else {
+						tx.EffectiveFromIdx = tx.FromIdx
+					}
 				}
 			}
 		}
@@ -802,6 +814,7 @@ // - blocks[].Rollup.Batch.L1CoordinatorTxs[].EthBlockNum
 // - blocks[].Rollup.Batch.L1CoordinatorTxs[].Position
 // - blocks[].Rollup.Batch.L1CoordinatorTxs[].EffectiveAmount
 // - blocks[].Rollup.Batch.L1CoordinatorTxs[].EffectiveDepositAmount
+// - blocks[].Rollup.Batch.L1CoordinatorTxs[].EffectiveFromIdx
 // - blocks[].Rollup.Batch.L2Txs[].TxID
 // - blocks[].Rollup.Batch.L2Txs[].Position
 // - blocks[].Rollup.Batch.L2Txs[].Nonce
@@ -839,15 +852,17 @@ for i := range blocks {
 		block := &blocks[i]
 		for j := range block.Rollup.Batches {
 			batch := &block.Rollup.Batches[j]
-			l1Txs := []common.L1Tx{}
+			l1Txs := []*common.L1Tx{}
 			if batch.L1Batch {
-				for _, tx := range tc.Queues[*batch.Batch.ForgeL1TxsNum] {
-					l1Txs = append(l1Txs, tx.L1Tx)
+				for k := range tc.Queues[*batch.Batch.ForgeL1TxsNum] {
+					l1Txs = append(l1Txs, &tc.Queues[*batch.Batch.ForgeL1TxsNum][k].L1Tx)
 				}
 			}
-			l1Txs = append(l1Txs, batch.L1CoordinatorTxs...)
+			for k := range batch.L1CoordinatorTxs {
+				l1Txs = append(l1Txs, &batch.L1CoordinatorTxs[k])
+			}
 			for k := range l1Txs {
-				tx := &l1Txs[k]
+				tx := l1Txs[k]
 				if tx.Type == common.TxTypeCreateAccountDeposit ||
 					tx.Type == common.TxTypeCreateAccountDepositTransfer {
 					user, ok := tc.UsersByIdx[tc.extra.idx]
@@ -864,6 +879,10 @@ EthAddr:  user.Addr,
 							Nonce:    0,
 							Balance:  big.NewInt(0),
 						})
+					if !tx.UserOrigin {
+						tx.EffectiveFromIdx = common.Idx(tc.extra.idx)
+					}
+					tc.extra.idxByTxID[tx.TxID] = common.Idx(tc.extra.idx)
 					tc.extra.idx++
 				}
 			}

@@ -154,10 +154,14 @@ &l1usertxs[i])
 		if err != nil {
 			return nil, tracerr.Wrap(err)
 		}
-		if tp.s.Typ == statedb.TypeSynchronizer && createdAccount != nil {
-			createdAccounts = append(createdAccounts, *createdAccount)
+		if tp.s.Typ == statedb.TypeSynchronizer {
+			if createdAccount != nil {
+				createdAccounts = append(createdAccounts, *createdAccount)
+				l1usertxs[i].EffectiveFromIdx = createdAccount.Idx
+			} else {
+				l1usertxs[i].EffectiveFromIdx = l1usertxs[i].FromIdx
+			}
 		}
-
 		if tp.zki != nil {
 			l1TxData, err := l1usertxs[i].BytesGeneric()
 			if err != nil {
@@ -201,8 +205,13 @@ }
 		if exitIdx != nil {
 			log.Error("Unexpected Exit in L1CoordinatorTx")
 		}
-		if tp.s.Typ == statedb.TypeSynchronizer && createdAccount != nil {
-			createdAccounts = append(createdAccounts, *createdAccount)
+		if tp.s.Typ == statedb.TypeSynchronizer {
+			if createdAccount != nil {
+				createdAccounts = append(createdAccounts, *createdAccount)
+				l1coordinatortxs[i].EffectiveFromIdx = createdAccount.Idx
+			} else {
+				l1coordinatortxs[i].EffectiveFromIdx = l1coordinatortxs[i].FromIdx
+			}
 		}
 		if tp.zki != nil {
 			l1TxData, err := l1coordinatortxs[i].BytesGeneric()