diff --git a/docs/database_schema.dbml b/docs/database_schema.dbml
index 75f1312..f97463e 100644
--- a/docs/database_schema.dbml
+++ b/docs/database_schema.dbml
@@ -294,8 +294,8 @@ Table custom_fields {
 Table membership_fee_types {
   id uuid [pk, not null, default: `uuid_generate_v7()`, note: 'UUIDv7 primary key']
   name text [not null, unique, note: 'Unique name for the fee type (e.g., "Standard", "Reduced")']
-  amount decimal [not null, note: 'Fee amount in default currency']
-  interval text [not null, note: 'Billing interval: monthly, quarterly, half_yearly, yearly (immutable)']
+  amount numeric(10,2) [not null, note: 'Fee amount in default currency (CHECK: >= 0)']
+  interval text [not null, note: 'Billing interval (CHECK: IN monthly, quarterly, half_yearly, yearly) - immutable']
   description text [null, note: 'Optional description for the fee type']
   
   indexes {
@@ -335,8 +335,8 @@ Table membership_fee_types {
 Table membership_fee_cycles {
   id uuid [pk, not null, default: `uuid_generate_v7()`, note: 'UUIDv7 primary key']
   cycle_start date [not null, note: 'Start date of the billing cycle']
-  amount decimal [not null, note: 'Fee amount for this cycle (historical record)']
-  status text [not null, default: 'unpaid', note: 'Payment status: unpaid, paid, suspended']
+  amount numeric(10,2) [not null, note: 'Fee amount for this cycle (CHECK: >= 0)']
+  status text [not null, default: 'unpaid', note: 'Payment status (CHECK: IN unpaid, paid, suspended)']
   notes text [null, note: 'Optional notes for this cycle']
   member_id uuid [not null, note: 'FK to members - the member this cycle belongs to']
   membership_fee_type_id uuid [not null, note: 'FK to membership_fee_types - fee type for this cycle']
diff --git a/lib/membership_fees/membership_fee_cycle.ex b/lib/membership_fees/membership_fee_cycle.ex
index 17539a1..98cd08d 100644
--- a/lib/membership_fees/membership_fee_cycle.ex
+++ b/lib/membership_fees/membership_fee_cycle.ex
@@ -65,7 +65,8 @@ defmodule Mv.MembershipFees.MembershipFeeCycle do
     attribute :amount, :decimal do
       allow_nil? false
       public? true
-      description "Fee amount for this cycle (stored for audit trail)"
+      description "Fee amount for this cycle (stored for audit trail, non-negative, max 2 decimal places)"
+      constraints min: 0, scale: 2
     end
 
     attribute :status, :atom do
diff --git a/lib/membership_fees/membership_fee_type.ex b/lib/membership_fees/membership_fee_type.ex
index 3d1cd68..877a385 100644
--- a/lib/membership_fees/membership_fee_type.ex
+++ b/lib/membership_fees/membership_fee_type.ex
@@ -63,7 +63,8 @@ defmodule Mv.MembershipFees.MembershipFeeType do
     attribute :amount, :decimal do
       allow_nil? false
       public? true
-      description "Fee amount in default currency"
+      description "Fee amount in default currency (non-negative, max 2 decimal places)"
+      constraints min: 0, scale: 2
     end
 
     attribute :interval, :atom do
diff --git a/priv/repo/migrations/20251211151449_add_membership_fees_tables.exs b/priv/repo/migrations/20251211151449_add_membership_fees_tables.exs
index eadc214..09af7c9 100644
--- a/priv/repo/migrations/20251211151449_add_membership_fees_tables.exs
+++ b/priv/repo/migrations/20251211151449_add_membership_fees_tables.exs
@@ -11,7 +11,8 @@ defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
     create table(:membership_fee_types, primary_key: false) do
       add :id, :uuid, null: false, default: fragment("uuid_generate_v7()"), primary_key: true
       add :name, :text, null: false
-      add :amount, :decimal, null: false
+      # Precision: 10 digits total, 2 decimal places (max 99,999,999.99)
+      add :amount, :numeric, null: false, precision: 10, scale: 2
       add :interval, :text, null: false
       add :description, :text
     end
@@ -20,10 +21,21 @@ defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
              name: "membership_fee_types_unique_name_index"
            )
 
+    # CHECK constraint for interval values (enforced at DB level)
+    create constraint(:membership_fee_types, :membership_fee_types_interval_check,
+             check: "interval IN ('monthly', 'quarterly', 'half_yearly', 'yearly')"
+           )
+
+    # CHECK constraint for non-negative amount
+    create constraint(:membership_fee_types, :membership_fee_types_amount_check,
+             check: "amount >= 0"
+           )
+
     create table(:membership_fee_cycles, primary_key: false) do
       add :id, :uuid, null: false, default: fragment("uuid_generate_v7()"), primary_key: true
       add :cycle_start, :date, null: false
-      add :amount, :decimal, null: false
+      # Precision: 10 digits total, 2 decimal places (max 99,999,999.99)
+      add :amount, :numeric, null: false, precision: 10, scale: 2
       add :status, :text, null: false, default: "unpaid"
       add :notes, :text
 
@@ -50,6 +62,16 @@ defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
           null: false
     end
 
+    # CHECK constraint for status values (enforced at DB level)
+    create constraint(:membership_fee_cycles, :membership_fee_cycles_status_check,
+             check: "status IN ('unpaid', 'paid', 'suspended')"
+           )
+
+    # CHECK constraint for non-negative amount
+    create constraint(:membership_fee_cycles, :membership_fee_cycles_amount_check,
+             check: "amount >= 0"
+           )
+
     # Indexes as specified in architecture document
     create index(:membership_fee_cycles, [:member_id])
     create index(:membership_fee_cycles, [:membership_fee_type_id])
@@ -102,6 +124,8 @@ defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
 
     drop constraint(:membership_fee_cycles, "membership_fee_cycles_member_id_fkey")
     drop constraint(:membership_fee_cycles, "membership_fee_cycles_membership_fee_type_id_fkey")
+    drop_if_exists constraint(:membership_fee_cycles, :membership_fee_cycles_status_check)
+    drop_if_exists constraint(:membership_fee_cycles, :membership_fee_cycles_amount_check)
 
     drop table(:membership_fee_cycles)
 
@@ -109,6 +133,8 @@ defmodule Mv.Repo.Migrations.AddMembershipFeesTables do
     drop_if_exists unique_index(:membership_fee_types, [:name],
                      name: "membership_fee_types_unique_name_index"
                    )
+    drop_if_exists constraint(:membership_fee_types, :membership_fee_types_interval_check)
+    drop_if_exists constraint(:membership_fee_types, :membership_fee_types_amount_check)
 
     drop table(:membership_fee_types)
   end
diff --git a/test/membership_fees/membership_fee_cycle_test.exs b/test/membership_fees/membership_fee_cycle_test.exs
index 570ed88..ca59e26 100644
--- a/test/membership_fees/membership_fee_cycle_test.exs
+++ b/test/membership_fees/membership_fee_cycle_test.exs
@@ -166,6 +166,30 @@ defmodule Mv.MembershipFees.MembershipFeeCycleTest do
       assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
       assert error_on_field?(error, :status)
     end
+
+    test "rejects negative amount", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-04-01],
+        amount: Decimal.new("-50.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:error, error} = Ash.create(MembershipFeeCycle, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "accepts zero amount", %{member: member, fee_type: fee_type} do
+      attrs = %{
+        cycle_start: ~D[2025-05-01],
+        amount: Decimal.new("0.00"),
+        member_id: member.id,
+        membership_fee_type_id: fee_type.id
+      }
+
+      assert {:ok, cycle} = Ash.create(MembershipFeeCycle, attrs)
+      assert Decimal.equal?(cycle.amount, Decimal.new("0.00"))
+    end
   end
 
   describe "uniqueness constraint" do
diff --git a/test/membership_fees/membership_fee_type_test.exs b/test/membership_fees/membership_fee_type_test.exs
index 5d053cc..9ca6f0a 100644
--- a/test/membership_fees/membership_fee_type_test.exs
+++ b/test/membership_fees/membership_fee_type_test.exs
@@ -103,6 +103,24 @@ defmodule Mv.MembershipFees.MembershipFeeTypeTest do
       # Check for uniqueness error
       assert error_on_field?(error, :name)
     end
+
+    test "rejects negative amount" do
+      attrs = %{name: "Negative Test", amount: Decimal.new("-10.00"), interval: :yearly}
+      assert {:error, error} = Ash.create(MembershipFeeType, attrs)
+      assert error_on_field?(error, :amount)
+    end
+
+    test "accepts zero amount" do
+      attrs = %{name: "Zero Amount", amount: Decimal.new("0.00"), interval: :yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert Decimal.equal?(fee_type.amount, Decimal.new("0.00"))
+    end
+
+    test "amount respects scale of 2 decimal places" do
+      attrs = %{name: "Scale Test", amount: Decimal.new("100.50"), interval: :yearly}
+      assert {:ok, fee_type} = Ash.create(MembershipFeeType, attrs)
+      assert Decimal.equal?(fee_type.amount, Decimal.new("100.50"))
+    end
   end
 
   describe "update MembershipFeeType" do