diff --git a/apps/api/internal/migration/migration.go b/apps/api/internal/migration/migration.go
index d9f5eed..3f22e6d 100644
--- a/apps/api/internal/migration/migration.go
+++ b/apps/api/internal/migration/migration.go
@@ -41,6 +41,9 @@ var m010 string
 //go:embed sql/011_credit_bills.sql
 var m011 string
 
+//go:embed sql/012_category_is_tax.sql
+var m012 string
+
 func Run(ctx context.Context, pool *pgxpool.Pool) error {
 	// Bootstrap: ensure schema_migrations table exists before checking versions.
 	if _, err := pool.Exec(ctx, `
@@ -52,7 +55,7 @@ func Run(ctx context.Context, pool *pgxpool.Pool) error {
 		return fmt.Errorf("bootstrap schema_migrations: %w", err)
 	}
 
-	migrations := []string{m001, m002, m003, m004, m005, m006, m007, m008, m009, m010, m011}
+	migrations := []string{m001, m002, m003, m004, m005, m006, m007, m008, m009, m010, m011, m012}
 	for i, sql := range migrations {
 		version := i + 1
 		var applied bool
diff --git a/apps/api/internal/migration/sql/012_category_is_tax.sql b/apps/api/internal/migration/sql/012_category_is_tax.sql
new file mode 100644
index 0000000..3a947cf
--- /dev/null
+++ b/apps/api/internal/migration/sql/012_category_is_tax.sql
@@ -0,0 +1 @@
+ALTER TABLE categories ADD COLUMN IF NOT EXISTS is_tax BOOLEAN NOT NULL DEFAULT FALSE;
diff --git a/apps/api/internal/model/category.go b/apps/api/internal/model/category.go
index 18f3162..d16309f 100644
--- a/apps/api/internal/model/category.go
+++ b/apps/api/internal/model/category.go
@@ -7,6 +7,7 @@ type Category struct {
 	Name      string    `json:"name"`
 	Color     string    `json:"color"`
 	IsDefault bool      `json:"is_default"`
+	IsTax     bool      `json:"is_tax"`
 	CreatedAt time.Time `json:"created_at"`
 	UpdatedAt time.Time `json:"updated_at"`
 }
@@ -14,4 +15,5 @@ type Category struct {
 type CategoryInput struct {
 	Name  string `json:"name"`
 	Color string `json:"color"`
+	IsTax bool   `json:"is_tax"`
 }
diff --git a/apps/api/internal/repository/category.go b/apps/api/internal/repository/category.go
index 8e2d7d8..4c2b49a 100644
--- a/apps/api/internal/repository/category.go
+++ b/apps/api/internal/repository/category.go
@@ -15,8 +15,8 @@ var ErrNotFound = errors.New("not found")
 type CategoryRepository interface {
 	List(ctx context.Context) ([]model.Category, error)
 	GetByID(ctx context.Context, id int) (*model.Category, error)
-	Create(ctx context.Context, name, color string) (*model.Category, error)
-	Update(ctx context.Context, id int, name, color string) (*model.Category, error)
+	Create(ctx context.Context, name, color string, isTax bool) (*model.Category, error)
+	Update(ctx context.Context, id int, name, color string, isTax bool) (*model.Category, error)
 	Delete(ctx context.Context, id int) error
 	HasTransactions(ctx context.Context, id int) (bool, error)
 }
@@ -29,7 +29,7 @@ func NewCategoryRepository(db *pgxpool.Pool) CategoryRepository {
 
 func (r *categoryRepo) List(ctx context.Context) ([]model.Category, error) {
 	rows, err := r.db.Query(ctx, `
-		SELECT id, name, color, is_default, created_at, updated_at
+		SELECT id, name, color, is_default, is_tax, created_at, updated_at
 		FROM categories
 		ORDER BY is_default DESC, name ASC`)
 	if err != nil {
@@ -40,7 +40,7 @@ func (r *categoryRepo) List(ctx context.Context) ([]model.Category, error) {
 	var out []model.Category
 	for rows.Next() {
 		var c model.Category
-		if err := rows.Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.CreatedAt, &c.UpdatedAt); err != nil {
+		if err := rows.Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.IsTax, &c.CreatedAt, &c.UpdatedAt); err != nil {
 			return nil, err
 		}
 		out = append(out, c)
@@ -51,35 +51,35 @@ func (r *categoryRepo) List(ctx context.Context) ([]model.Category, error) {
 func (r *categoryRepo) GetByID(ctx context.Context, id int) (*model.Category, error) {
 	var c model.Category
 	err := r.db.QueryRow(ctx, `
-		SELECT id, name, color, is_default, created_at, updated_at
+		SELECT id, name, color, is_default, is_tax, created_at, updated_at
 		FROM categories WHERE id = $1`, id).
-		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.CreatedAt, &c.UpdatedAt)
+		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.IsTax, &c.CreatedAt, &c.UpdatedAt)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return nil, ErrNotFound
 	}
 	return &c, err
 }
 
-func (r *categoryRepo) Create(ctx context.Context, name, color string) (*model.Category, error) {
+func (r *categoryRepo) Create(ctx context.Context, name, color string, isTax bool) (*model.Category, error) {
 	var c model.Category
 	err := r.db.QueryRow(ctx, `
-		INSERT INTO categories (name, color)
-		VALUES ($1, $2)
-		RETURNING id, name, color, is_default, created_at, updated_at`,
-		name, color).
-		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.CreatedAt, &c.UpdatedAt)
+		INSERT INTO categories (name, color, is_tax)
+		VALUES ($1, $2, $3)
+		RETURNING id, name, color, is_default, is_tax, created_at, updated_at`,
+		name, color, isTax).
+		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.IsTax, &c.CreatedAt, &c.UpdatedAt)
 	return &c, err
 }
 
-func (r *categoryRepo) Update(ctx context.Context, id int, name, color string) (*model.Category, error) {
+func (r *categoryRepo) Update(ctx context.Context, id int, name, color string, isTax bool) (*model.Category, error) {
 	var c model.Category
 	err := r.db.QueryRow(ctx, `
 		UPDATE categories
-		SET name = $1, color = $2, updated_at = NOW()
-		WHERE id = $3
-		RETURNING id, name, color, is_default, created_at, updated_at`,
-		name, color, id).
-		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.CreatedAt, &c.UpdatedAt)
+		SET name = $1, color = $2, is_tax = $3, updated_at = NOW()
+		WHERE id = $4
+		RETURNING id, name, color, is_default, is_tax, created_at, updated_at`,
+		name, color, isTax, id).
+		Scan(&c.ID, &c.Name, &c.Color, &c.IsDefault, &c.IsTax, &c.CreatedAt, &c.UpdatedAt)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return nil, ErrNotFound
 	}
diff --git a/apps/api/internal/repository/dashboard.go b/apps/api/internal/repository/dashboard.go
index 3d1abed..9a26be0 100644
--- a/apps/api/internal/repository/dashboard.go
+++ b/apps/api/internal/repository/dashboard.go
@@ -90,6 +90,19 @@ func (r *DashboardRepository) MonthlyEvolution(ctx context.Context, month string
 	return out, rows.Err()
 }
 
+func (r *DashboardRepository) TotalTaxes(ctx context.Context, month string) (float64, error) {
+	var total float64
+	err := r.pool.QueryRow(ctx, `
+		SELECT COALESCE(SUM(t.amount), 0)
+		FROM transactions t
+		JOIN categories c ON c.id = t.category_id
+		WHERE to_char(t.date, 'YYYY-MM') = $1
+		  AND t.type = 'expense'
+		  AND c.is_tax = TRUE
+	`, month).Scan(&total)
+	return total, err
+}
+
 func (r *DashboardRepository) RecentTransactions(ctx context.Context, month string) ([]model.RecentTransaction, error) {
 	rows, err := r.pool.Query(ctx, `
 		SELECT
diff --git a/apps/api/internal/service/category.go b/apps/api/internal/service/category.go
index f46224b..49cd817 100644
--- a/apps/api/internal/service/category.go
+++ b/apps/api/internal/service/category.go
@@ -32,14 +32,14 @@ func (s *CategoryService) Create(ctx context.Context, in model.CategoryInput) (*
 	if err := validateInput(in); err != nil {
 		return nil, err
 	}
-	return s.repo.Create(ctx, strings.TrimSpace(in.Name), in.Color)
+	return s.repo.Create(ctx, strings.TrimSpace(in.Name), in.Color, in.IsTax)
 }
 
 func (s *CategoryService) Update(ctx context.Context, id int, in model.CategoryInput) (*model.Category, error) {
 	if err := validateInput(in); err != nil {
 		return nil, err
 	}
-	return s.repo.Update(ctx, id, strings.TrimSpace(in.Name), in.Color)
+	return s.repo.Update(ctx, id, strings.TrimSpace(in.Name), in.Color, in.IsTax)
 }
 
 func (s *CategoryService) Delete(ctx context.Context, id int) error {
diff --git a/apps/api/internal/service/dashboard.go b/apps/api/internal/service/dashboard.go
index 10520fb..b0800ad 100644
--- a/apps/api/internal/service/dashboard.go
+++ b/apps/api/internal/service/dashboard.go
@@ -8,6 +8,7 @@ import (
 
 type DashboardRepo interface {
 	MonthlySummary(ctx context.Context, month string) (income, expenses float64, err error)
+	TotalTaxes(ctx context.Context, month string) (float64, error)
 	ByCategory(ctx context.Context, month string) ([]model.CategoryTotal, error)
 	MonthlyEvolution(ctx context.Context, month string) ([]model.MonthEvolution, error)
 	RecentTransactions(ctx context.Context, month string) ([]model.RecentTransaction, error)
@@ -34,6 +35,11 @@ func (s *DashboardService) Get(ctx context.Context, month string) (*model.Dashbo
 		return nil, err
 	}
 
+	taxes, err := s.repo.TotalTaxes(ctx, month)
+	if err != nil {
+		return nil, err
+	}
+
 	byCategory, err := s.repo.ByCategory(ctx, month)
 	if err != nil {
 		return nil, err
@@ -49,9 +55,11 @@ func (s *DashboardService) Get(ctx context.Context, month string) (*model.Dashbo
 		return nil, err
 	}
 
+	// savings_pct uses net income (gross - taxes) as denominator (Option B)
 	var savingsPct float64
-	if income > 0 {
-		savingsPct = (income - expenses) / income * 100
+	netIncome := income - taxes
+	if netIncome > 0 {
+		savingsPct = (income - expenses) / netIncome * 100
 	}
 
 	statuses, err := s.recurrSvc.MonthlyStatus(ctx, month)
diff --git a/apps/api/internal/service/dashboard_test.go b/apps/api/internal/service/dashboard_test.go
index 250566f..5689934 100644
--- a/apps/api/internal/service/dashboard_test.go
+++ b/apps/api/internal/service/dashboard_test.go
@@ -16,6 +16,9 @@ type mockDashboardRepo struct {
 func (m *mockDashboardRepo) MonthlySummary(_ context.Context, _ string) (float64, float64, error) {
 	return m.income, m.expenses, nil
 }
+func (m *mockDashboardRepo) TotalTaxes(_ context.Context, _ string) (float64, error) {
+	return 0, nil
+}
 func (m *mockDashboardRepo) ByCategory(_ context.Context, _ string) ([]model.CategoryTotal, error) {
 	return nil, nil
 }
diff --git a/apps/web/src/stores/categories.ts b/apps/web/src/stores/categories.ts
index b3ce1c4..e19795f 100644
--- a/apps/web/src/stores/categories.ts
+++ b/apps/web/src/stores/categories.ts
@@ -7,6 +7,7 @@ export interface Category {
   name: string
   color: string
   is_default: boolean
+  is_tax: boolean
   created_at: string
   updated_at: string
 }
@@ -28,14 +29,14 @@ export const useCategoriesStore = defineStore('categories', () => {
     }
   }
 
-  async function create(name: string, color: string) {
-    const cat = await api.post<Category>('/categories', { name, color })
+  async function create(name: string, color: string, isTax = false) {
+    const cat = await api.post<Category>('/categories', { name, color, is_tax: isTax })
     categories.value.push(cat)
     return cat
   }
 
-  async function update(id: number, name: string, color: string) {
-    const cat = await api.put<Category>(`/categories/${id}`, { name, color })
+  async function update(id: number, name: string, color: string, isTax = false) {
+    const cat = await api.put<Category>(`/categories/${id}`, { name, color, is_tax: isTax })
     const idx = categories.value.findIndex((c) => c.id === id)
     if (idx !== -1) categories.value[idx] = cat
     return cat
diff --git a/apps/web/src/views/CategoriesView.vue b/apps/web/src/views/CategoriesView.vue
index 372a32e..0429715 100644
--- a/apps/web/src/views/CategoriesView.vue
+++ b/apps/web/src/views/CategoriesView.vue
@@ -6,19 +6,19 @@ import NeonPanel from '@/components/NeonPanel.vue'
 const store = useCategoriesStore()
 onMounted(() => store.fetchAll())
 
-const form = ref({ name: '', color: '#a855f7' })
+const form = ref({ name: '', color: '#a855f7', is_tax: false })
 const editId = ref<number | null>(null)
 const formError = ref<string | null>(null)
 
-function startEdit(id: number, name: string, color: string) {
+function startEdit(id: number, name: string, color: string, isTax: boolean) {
   editId.value = id
-  form.value = { name, color }
+  form.value = { name, color, is_tax: isTax }
   formError.value = null
 }
 
 function cancelEdit() {
   editId.value = null
-  form.value = { name: '', color: '#a855f7' }
+  form.value = { name: '', color: '#a855f7', is_tax: false }
   formError.value = null
 }
 
@@ -26,11 +26,11 @@ async function submit() {
   formError.value = null
   try {
     if (editId.value !== null) {
-      await store.update(editId.value, form.value.name, form.value.color)
+      await store.update(editId.value, form.value.name, form.value.color, form.value.is_tax)
       cancelEdit()
     } else {
-      await store.create(form.value.name, form.value.color)
-      form.value = { name: '', color: '#a855f7' }
+      await store.create(form.value.name, form.value.color, form.value.is_tax)
+      form.value = { name: '', color: '#a855f7', is_tax: false }
     }
   } catch (e: any) {
     formError.value = e.message
@@ -61,6 +61,10 @@ async function remove(id: number, name: string) {
             <input type="color" v-model="form.color" class="fc-color-input" />
             <span class="fc-mono fc-cat-form__hex">{{ form.color }}</span>
           </div>
+          <label class="fc-cat-form__tax fc-mono">
+            <input type="checkbox" v-model="form.is_tax" />
+            IMPOSTO
+          </label>
         </div>
         <p v-if="formError" class="fc-cat-form__error fc-mono">{{ formError }}</p>
         <div class="fc-cat-form__actions">
@@ -84,8 +88,9 @@ async function remove(id: number, name: string) {
           <span class="fc-cat-item__dot" :style="{ background: cat.color }" />
           <span class="fc-body fc-cat-item__name">{{ cat.name }}</span>
           <span v-if="cat.is_default" class="fc-pixel fc-cat-item__default">PADRÃO</span>
+          <span v-if="cat.is_tax" class="fc-pixel fc-cat-item__tax">IMPOSTO</span>
           <div class="fc-cat-item__actions">
-            <button class="fc-btn fc-btn--sm fc-btn--ghost" @click="startEdit(cat.id, cat.name, cat.color)">EDITAR</button>
+            <button class="fc-btn fc-btn--sm fc-btn--ghost" @click="startEdit(cat.id, cat.name, cat.color, cat.is_tax)">EDITAR</button>
             <button
               v-if="!cat.is_default"
               class="fc-btn fc-btn--sm fc-btn--danger"
@@ -211,5 +216,24 @@ async function remove(id: number, name: string) {
   border-radius: 2px;
 }
 
+.fc-cat-item__tax {
+  font-size: 6px;
+  color: var(--fc-gold);
+  background: rgba(255,180,0,.15);
+  border: 1px solid rgba(255,180,0,.4);
+  padding: 3px 6px;
+  border-radius: 2px;
+}
+
+.fc-cat-form__tax {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  font-size: 10px;
+  color: var(--fc-text-dim);
+  cursor: pointer;
+  flex-shrink: 0;
+}
+
 .fc-cat-item__actions { display: flex; gap: var(--fc-space-1); }
 </style>