diff --git a/API/ROLAC.API/Data/AppDbContext.cs b/API/ROLAC.API/Data/AppDbContext.cs
index b4efd40..7360594 100644
--- a/API/ROLAC.API/Data/AppDbContext.cs
+++ b/API/ROLAC.API/Data/AppDbContext.cs
@@ -20,6 +20,7 @@ public class AppDbContext : IdentityDbContext<AppUser, AppRole, string>
     public DbSet<Ministry>        Ministries        => Set<Ministry>();
     public DbSet<ExpenseCategoryGroup> ExpenseCategoryGroups => Set<ExpenseCategoryGroup>();
     public DbSet<ExpenseSubCategory>   ExpenseSubCategories  => Set<ExpenseSubCategory>();
+    public DbSet<Form990ExpenseLine> Form990ExpenseLines => Set<Form990ExpenseLine>();
     public DbSet<Expense>          Expenses          => Set<Expense>();
     public DbSet<MonthlyStatement> MonthlyStatements => Set<MonthlyStatement>();
     public DbSet<ChurchProfile>    ChurchProfiles    => Set<ChurchProfile>();
@@ -202,6 +203,17 @@ public class AppDbContext : IdentityDbContext<AppUser, AppRole, string>
             entity.Property(e => e.Name_zh).HasMaxLength(200);
         });
 
+        // ── Form990ExpenseLine (Part IX natural-expense line catalog) ─────────
+        builder.Entity<Form990ExpenseLine>(entity =>
+        {
+            entity.Property(e => e.LineCode).HasMaxLength(10).IsRequired();
+            entity.Property(e => e.Name_en).HasMaxLength(200).IsRequired();
+            entity.Property(e => e.Name_zh).HasMaxLength(200);
+            entity.Property(e => e.CreatedBy).HasMaxLength(450);
+            entity.Property(e => e.UpdatedBy).HasMaxLength(450);
+            entity.HasIndex(e => e.LineCode).IsUnique();
+        });
+
         // ── ExpenseCategoryGroup ─────────────────────────────────────────────
         builder.Entity<ExpenseCategoryGroup>(entity =>
         {
diff --git a/API/ROLAC.API/Entities/Form990ExpenseLine.cs b/API/ROLAC.API/Entities/Form990ExpenseLine.cs
new file mode 100644
index 0000000..d8e5781
--- /dev/null
+++ b/API/ROLAC.API/Entities/Form990ExpenseLine.cs
@@ -0,0 +1,13 @@
+using ROLAC.API.Entities.Base;
+namespace ROLAC.API.Entities;
+
+/// <summary>A row of IRS Form 990 Part IX (natural expense line), e.g. "7 — Other salaries and wages".</summary>
+public class Form990ExpenseLine : AuditableEntity, IAuditable
+{
+    public int     Id        { get; set; }
+    public string  LineCode  { get; set; } = null!;   // "7", "11b", "16", "24"
+    public string  Name_en   { get; set; } = null!;
+    public string? Name_zh   { get; set; }
+    public int     SortOrder { get; set; }
+    public bool    IsActive  { get; set; } = true;
+}
diff --git a/API/ROLAC.API/Entities/FunctionalClasses.cs b/API/ROLAC.API/Entities/FunctionalClasses.cs
new file mode 100644
index 0000000..45d8b85
--- /dev/null
+++ b/API/ROLAC.API/Entities/FunctionalClasses.cs
@@ -0,0 +1,18 @@
+namespace ROLAC.API.Entities;
+
+/// <summary>
+/// The three IRS Form 990 Part IX functional-expense columns. Stored verbatim in
+/// Ministry.DefaultFunctionalClass and Expense.FunctionalClass.
+/// </summary>
+public static class FunctionalClasses
+{
+    public const string Program           = "Program";
+    public const string ManagementGeneral = "ManagementGeneral";
+    public const string Fundraising       = "Fundraising";
+
+    public static readonly IReadOnlyList<string> All = [Program, ManagementGeneral, Fundraising];
+
+    /// <summary>Returns the value if valid, otherwise Program (the safe default).</summary>
+    public static string Normalize(string? value) =>
+        value is not null && All.Contains(value) ? value : Program;
+}