diff --git a/app/models/transaction.rb b/app/models/transaction.rb
index 1e3954a..436cd01 100644
--- a/app/models/transaction.rb
+++ b/app/models/transaction.rb
@@ -1,3 +1,32 @@
 class Transaction < ApplicationRecord
   belongs_to :user
+  # Validaciones de atributos
+  validates :user_id, :coin_to_send, :coin_to_receive, :amount_to_send_in_cents_or_sats,
+            :amount_to_receive_in_cents_or_sats, :btc_usd_exchange_rate, presence: true
+  # Validaciones personalizadas
+  validate :minimal_amount_to_send
+  validate :avoid_transaction_if_insuficient_balance
+
+  private
+
+  def minimal_amount_to_send
+    if coin_to_send == 'usd' && amount_to_send_in_cents_or_sats < 1000
+      errors.add(:minimal_amount,
+                 'La cantidad mínima a enviar debe ser de 1 000 cents o superior')
+    end
+    return unless coin_to_send == 'btc' && amount_to_send_in_cents_or_sats < 14_000
+
+    errors.add(:minimal_amount,
+               'La cantidad mínima a enviar debe ser de 14 000 sats o superior')
+  end
+
+  def avoid_transaction_if_insuficient_balance
+    @user = User.find(user_id)
+    if coin_to_send == 'usd' && @user.usd_balance_in_cents < amount_to_send_in_cents_or_sats
+      errors.add(:insuficient_balance, 'No tiene fondos en USD suficientes para realizar esta transacción')
+    end
+    return unless coin_to_send == 'btc' && @user.btc_balance_in_sats < amount_to_send_in_cents_or_sats
+
+    errors.add(:insuficient_balance, 'No tiene fondos suficientes en BTC para realizar esta transacción')
+  end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 3fb70cf..a4c0194 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,3 +1,16 @@
 class User < ApplicationRecord
   has_many :transactions
+  # Validaciones de atributos
+  validates :name, :year_of_birth, :usd_balance_in_cents, :btc_balance_in_sats, presence: true
+  validates :usd_balance_in_cents, :btc_balance_in_sats, numericality: { greater_than_or_equal_to: 0 }
+  # Validaciones personalizadas
+  validate :must_be_of_legal_age
+
+  private
+
+  def must_be_of_legal_age
+    return unless year_of_birth.present? && Date.current.year - year_of_birth < 18
+
+    errors.add(:year_of_birth, 'El usuario debe ser mayor de edad para registrase')
+  end
 end