Phase F: Customer/Vendor Statements, Payment Terms Parser, Tax Rates

F1: GetCustomerStatementAsync/GetVendorStatementAsync on IFinancialReportService;
    StatementLineDto; CustomerStatementDto/VendorStatementDto; Statement action on
    CustomersController + VendorsController; Statement views + PDF download via
    StatementPdfHelper (QuestPDF); Statement button on Customer/Vendor Details pages.

F2: PaymentTermsParser static helper (CalculateDueDate, ParseEarlyPaymentDiscount);
    EarlyPaymentDiscountPercent/Days on Invoice entity; GetCustomerPaymentTerms AJAX
    endpoint on InvoicesController auto-populates Terms + due date on customer select;
    early payment discount notice on Invoice Create.

F3: TaxRate entity (Name/Rate/State/IsDefault/IsActive, tenant-filtered);
    IUnitOfWork.TaxRates + UnitOfWork + ApplicationDbContext; TaxRatesController
    (Index/Create/Edit/Delete/ToggleActive, CompanyAdminOnly); GetTaxRateForCustomer
    AJAX endpoint; Tax Rates in Settings gear menu.

Also fixes AddVendorCredits migration: VendorCreditApplications FKs changed from
CASCADE to NoAction to resolve SQL Server error 1785 (multiple cascade paths).
Migration: AddPaymentTermsAndTaxRates applied locally; 200/200 unit tests pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -332,6 +332,9 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Bank reconciliation sessions matching GL transactions to bank statements; tenant-filtered with soft delete.</summary>
     public DbSet<BankReconciliation> BankReconciliations { get; set; }
 
+    /// <summary>Named tax rates used to pre-fill invoice tax percent by jurisdiction; tenant-filtered with soft delete.</summary>
+    public DbSet<TaxRate> TaxRates { get; set; }
+
     /// <summary>Credit notes received from vendors (returned goods, pricing disputes); tenant-filtered with soft delete.</summary>
     public DbSet<VendorCredit> VendorCredits { get; set; }
     /// <summary>Expense-reversal line items on a vendor credit; soft-delete only.</summary>
@@ -638,12 +641,29 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
         modelBuilder.Entity<BankReconciliation>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
 
+        // Tax Rates: tenant-filtered
+        modelBuilder.Entity<TaxRate>().HasQueryFilter(e =>
+            !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
+
         // Vendor Credits: tenant-filtered; child rows soft-delete only
         modelBuilder.Entity<VendorCredit>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
         modelBuilder.Entity<VendorCreditLineItem>().HasQueryFilter(e => !e.IsDeleted);
         modelBuilder.Entity<VendorCreditApplication>().HasQueryFilter(e => !e.IsDeleted);
 
+        // VendorCreditApplication: NoAction on both FKs to avoid SQL Server multiple-cascade-path error 1785.
+        // Bills and VendorCredits both cascade-delete through Vendor, creating two paths to VendorCreditApplications.
+        modelBuilder.Entity<VendorCreditApplication>()
+            .HasOne(vca => vca.Bill)
+            .WithMany()
+            .HasForeignKey(vca => vca.BillId)
+            .OnDelete(DeleteBehavior.NoAction);
+        modelBuilder.Entity<VendorCreditApplication>()
+            .HasOne(vca => vca.VendorCredit)
+            .WithMany()
+            .HasForeignKey(vca => vca.VendorCreditId)
+            .OnDelete(DeleteBehavior.NoAction);
+
         // Purchase Orders
         modelBuilder.Entity<PurchaseOrder>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));

src/PowderCoating.Infrastructure/Migrations/20260510035830_AddVendorCredits.cs

@@ -78,13 +78,13 @@ namespace PowderCoating.Infrastructure.Migrations
                         column: x => x.BillId,
                         principalTable: "Bills",
                         principalColumn: "Id",
-                        onDelete: ReferentialAction.Cascade);
+                        onDelete: ReferentialAction.NoAction);
                     table.ForeignKey(
                         name: "FK_VendorCreditApplications_VendorCredits_VendorCreditId",
                         column: x => x.VendorCreditId,
                         principalTable: "VendorCredits",
                         principalColumn: "Id",
-                        onDelete: ReferentialAction.Cascade);
+                        onDelete: ReferentialAction.NoAction);
                 });
 
             migrationBuilder.CreateTable(

src/PowderCoating.Infrastructure/Migrations/20260510144855_AddPaymentTermsAndTaxRates.cs

@@ -0,0 +1,112 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PowderCoating.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddPaymentTermsAndTaxRates : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "EarlyPaymentDiscountDays",
+                table: "Invoices",
+                type: "int",
+                nullable: false,
+                defaultValue: 0);
+
+            migrationBuilder.AddColumn<decimal>(
+                name: "EarlyPaymentDiscountPercent",
+                table: "Invoices",
+                type: "decimal(18,2)",
+                nullable: false,
+                defaultValue: 0m);
+
+            migrationBuilder.CreateTable(
+                name: "TaxRates",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "int", nullable: false)
+                        .Annotation("SqlServer:Identity", "1, 1"),
+                    Name = table.Column<string>(type: "nvarchar(max)", nullable: false),
+                    Rate = table.Column<decimal>(type: "decimal(18,2)", nullable: false),
+                    State = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    Description = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    IsDefault = table.Column<bool>(type: "bit", nullable: false),
+                    IsActive = table.Column<bool>(type: "bit", nullable: false),
+                    CompanyId = table.Column<int>(type: "int", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "datetime2", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    CreatedBy = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    UpdatedBy = table.Column<string>(type: "nvarchar(max)", nullable: true),
+                    IsDeleted = table.Column<bool>(type: "bit", nullable: false),
+                    DeletedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    DeletedBy = table.Column<string>(type: "nvarchar(max)", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_TaxRates", x => x.Id);
+                });
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3903));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3909));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3910));
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "TaxRates");
+
+            migrationBuilder.DropColumn(
+                name: "EarlyPaymentDiscountDays",
+                table: "Invoices");
+
+            migrationBuilder.DropColumn(
+                name: "EarlyPaymentDiscountPercent",
+                table: "Invoices");
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 1,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8472));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 2,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8478));
+
+            migrationBuilder.UpdateData(
+                table: "PricingTiers",
+                keyColumn: "Id",
+                keyValue: 3,
+                column: "CreatedAt",
+                value: new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8479));
+        }
+    }
+}

src/PowderCoating.Infrastructure/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -3586,6 +3586,12 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.Property<DateTime?>("DueDate")
                         .HasColumnType("datetime2");
 
+                    b.Property<int>("EarlyPaymentDiscountDays")
+                        .HasColumnType("int");
+
+                    b.Property<decimal>("EarlyPaymentDiscountPercent")
+                        .HasColumnType("decimal(18,2)");
+
                     b.Property<string>("ExternalReference")
                         .HasColumnType("nvarchar(450)");
 
@@ -6287,7 +6293,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 1,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8472),
+                            CreatedAt = new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3903),
                             Description = "Standard pricing for regular customers",
                             DiscountPercent = 0m,
                             IsActive = true,
@@ -6298,7 +6304,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 2,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8478),
+                            CreatedAt = new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3909),
                             Description = "5% discount for preferred customers",
                             DiscountPercent = 5m,
                             IsActive = true,
@@ -6309,7 +6315,7 @@ namespace PowderCoating.Infrastructure.Migrations
                         {
                             Id = 3,
                             CompanyId = 0,
-                            CreatedAt = new DateTime(2026, 5, 10, 4, 6, 6, 200, DateTimeKind.Utc).AddTicks(8479),
+                            CreatedAt = new DateTime(2026, 5, 10, 14, 48, 51, 545, DateTimeKind.Utc).AddTicks(3910),
                             Description = "10% discount for premium customers",
                             DiscountPercent = 10m,
                             IsActive = true,
@@ -7742,6 +7748,62 @@ namespace PowderCoating.Infrastructure.Migrations
                     b.ToTable("SubscriptionPlanConfigs");
                 });
 
+            modelBuilder.Entity("PowderCoating.Core.Entities.TaxRate", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
+
+                    b.Property<int>("CompanyId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("CreatedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<DateTime?>("DeletedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("DeletedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<bool>("IsActive")
+                        .HasColumnType("bit");
+
+                    b.Property<bool>("IsDefault")
+                        .HasColumnType("bit");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<decimal>("Rate")
+                        .HasColumnType("decimal(18,2)");
+
+                    b.Property<string>("State")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<string>("UpdatedBy")
+                        .HasColumnType("nvarchar(max)");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("TaxRates");
+                });
+
             modelBuilder.Entity("PowderCoating.Core.Entities.TermsAcceptance", b =>
                 {
                     b.Property<int>("Id")

src/PowderCoating.Infrastructure/Repositories/UnitOfWork.cs

@@ -154,6 +154,9 @@ public class UnitOfWork : IUnitOfWork
     // Bank Reconciliation
     private IRepository<BankReconciliation>? _bankReconciliations;
 
+    // Tax Rates
+    private IRepository<TaxRate>? _taxRates;
+
     /// <summary>
     /// Initialises the unit of work with the scoped <paramref name="context"/>.
     /// The context is shared across all repositories created by this instance so that
@@ -552,6 +555,11 @@ public class UnitOfWork : IUnitOfWork
     public IRepository<BankReconciliation> BankReconciliations =>
         _bankReconciliations ??= new Repository<BankReconciliation>(_context);
 
+    // Tax Rates
+    /// <summary>Repository for <see cref="TaxRate"/> named tax rates used to pre-fill invoice tax percent by jurisdiction.</summary>
+    public IRepository<TaxRate> TaxRates =>
+        _taxRates ??= new Repository<TaxRate>(_context);
+
     /// <summary>
     /// Flushes all pending changes in the EF Core change tracker to the database.
     /// Returns the number of state entries written.

src/PowderCoating.Infrastructure/Services/FinancialReportService.cs

@@ -713,6 +713,218 @@ public class FinancialReportService : IFinancialReportService
         return method ?? AccountingMethod.Accrual;
     }
 
+    /// <inheritdoc/>
+    public async Task<CustomerStatementDto> GetCustomerStatementAsync(int companyId, int customerId, DateTime from, DateTime to)
+    {
+        var toEnd   = to.AddDays(1).AddTicks(-1);
+        var fromEnd = from.AddTicks(-1);  // exclusive upper bound for pre-period queries
+
+        var companyName = await GetCompanyNameAsync(companyId);
+
+        var customer = await _context.Customers
+            .Where(c => c.Id == customerId && c.CompanyId == companyId)
+            .AsNoTracking().FirstOrDefaultAsync();
+        if (customer == null) return new CustomerStatementDto { CompanyName = companyName, From = from, To = to };
+
+        var customerName = customer.IsCommercial
+            ? customer.CompanyName ?? string.Empty
+            : $"{customer.ContactFirstName} {customer.ContactLastName}".Trim();
+
+        var address = string.Join(", ", new[] { customer.Address, customer.City, customer.State, customer.ZipCode }
+            .Where(s => !string.IsNullOrWhiteSpace(s)));
+
+        // Opening balance: invoiced − paid before period start
+        var preInvoiced = await _context.Invoices
+            .Where(i => i.CustomerId == customerId
+                     && i.Status != InvoiceStatus.Draft && i.Status != InvoiceStatus.Voided
+                     && i.InvoiceDate < from)
+            .SumAsync(i => (decimal?)i.Total) ?? 0;
+        var prePaid = await _context.Payments
+            .Where(p => p.Invoice.CustomerId == customerId
+                     && p.Invoice.Status != InvoiceStatus.Voided
+                     && p.PaymentDate < from)
+            .SumAsync(p => (decimal?)p.Amount) ?? 0;
+        var preCredits = await _context.CreditMemoApplications
+            .Where(a => a.Invoice.CustomerId == customerId && a.AppliedDate < from)
+            .SumAsync(a => (decimal?)a.AmountApplied) ?? 0;
+
+        var openingBalance = preInvoiced - prePaid - preCredits;
+
+        // In-period activity — gather, then sort, then compute running balance
+        var lines = new List<StatementLineDto>();
+
+        var periodInvoices = await _context.Invoices
+            .Where(i => i.CustomerId == customerId
+                     && i.Status != InvoiceStatus.Draft && i.Status != InvoiceStatus.Voided
+                     && i.InvoiceDate >= from && i.InvoiceDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var inv in periodInvoices)
+            lines.Add(new StatementLineDto
+            {
+                Date        = inv.InvoiceDate,
+                Type        = "Invoice",
+                Reference   = inv.InvoiceNumber,
+                Description = "Invoice",
+                Debit       = inv.Total,
+            });
+
+        var periodPayments = await _context.Payments
+            .Include(p => p.Invoice)
+            .Where(p => p.Invoice.CustomerId == customerId
+                     && p.Invoice.Status != InvoiceStatus.Voided
+                     && p.PaymentDate >= from && p.PaymentDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var pay in periodPayments)
+            lines.Add(new StatementLineDto
+            {
+                Date        = pay.PaymentDate,
+                Type        = "Payment",
+                Reference   = pay.Invoice.InvoiceNumber,
+                Description = pay.Notes ?? "Payment received",
+                Credit      = pay.Amount,
+            });
+
+        var periodCredits = await _context.CreditMemoApplications
+            .Include(a => a.Invoice)
+            .Include(a => a.CreditMemo)
+            .Where(a => a.Invoice.CustomerId == customerId
+                     && a.AppliedDate >= from && a.AppliedDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var cr in periodCredits)
+            lines.Add(new StatementLineDto
+            {
+                Date        = cr.AppliedDate,
+                Type        = "Credit Applied",
+                Reference   = cr.Invoice?.InvoiceNumber ?? string.Empty,
+                Description = $"Credit memo applied",
+                Credit      = cr.AmountApplied,
+            });
+
+        // Sort by date then compute running balance
+        lines = lines.OrderBy(l => l.Date).ThenBy(l => l.Type).ToList();
+        var running = openingBalance;
+        foreach (var line in lines)
+        {
+            running += (line.Debit ?? 0) - (line.Credit ?? 0);
+            line.RunningBalance = running;
+        }
+
+        return new CustomerStatementDto
+        {
+            CustomerId      = customerId,
+            CustomerName    = customerName,
+            CustomerAddress = address,
+            CompanyName     = companyName,
+            From            = from,
+            To              = to,
+            OpeningBalance  = openingBalance,
+            Lines           = lines,
+            ClosingBalance  = running,
+        };
+    }
+
+    /// <inheritdoc/>
+    public async Task<VendorStatementDto> GetVendorStatementAsync(int companyId, int vendorId, DateTime from, DateTime to)
+    {
+        var toEnd = to.AddDays(1).AddTicks(-1);
+
+        var companyName = await GetCompanyNameAsync(companyId);
+
+        var vendor = await _context.Vendors
+            .Where(v => v.Id == vendorId && v.CompanyId == companyId)
+            .AsNoTracking().FirstOrDefaultAsync();
+        if (vendor == null) return new VendorStatementDto { CompanyName = companyName, From = from, To = to };
+
+        // Opening balance: bills − payments − credits before period start
+        var preBills = await _context.Bills
+            .Where(b => b.VendorId == vendorId
+                     && b.Status != BillStatus.Draft && b.Status != BillStatus.Voided
+                     && b.BillDate < from)
+            .SumAsync(b => (decimal?)b.Total) ?? 0;
+        var prePayments = await _context.BillPayments
+            .Where(bp => bp.Bill.VendorId == vendorId && bp.PaymentDate < from)
+            .SumAsync(bp => (decimal?)bp.Amount) ?? 0;
+        var preVcApplied = await _context.VendorCreditApplications
+            .Where(vca => vca.Bill.VendorId == vendorId && vca.AppliedDate < from)
+            .SumAsync(vca => (decimal?)vca.Amount) ?? 0;
+
+        var openingBalance = preBills - prePayments - preVcApplied;
+
+        var lines = new List<StatementLineDto>();
+
+        var periodBills = await _context.Bills
+            .Where(b => b.VendorId == vendorId
+                     && b.Status != BillStatus.Draft && b.Status != BillStatus.Voided
+                     && b.BillDate >= from && b.BillDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var bill in periodBills)
+            lines.Add(new StatementLineDto
+            {
+                Date        = bill.BillDate,
+                Type        = "Bill",
+                Reference   = bill.BillNumber,
+                Description = bill.Memo ?? "Vendor bill",
+                Debit       = bill.Total,
+            });
+
+        var periodPayments = await _context.BillPayments
+            .Include(bp => bp.Bill)
+            .Where(bp => bp.Bill.VendorId == vendorId
+                      && bp.PaymentDate >= from && bp.PaymentDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var pay in periodPayments)
+            lines.Add(new StatementLineDto
+            {
+                Date        = pay.PaymentDate,
+                Type        = "Payment",
+                Reference   = pay.Bill.BillNumber,
+                Description = pay.Memo ?? "Bill payment",
+                Credit      = pay.Amount,
+            });
+
+        var periodVcApplied = await _context.VendorCreditApplications
+            .Include(vca => vca.VendorCredit)
+            .Include(vca => vca.Bill)
+            .Where(vca => vca.Bill.VendorId == vendorId
+                       && vca.AppliedDate >= from && vca.AppliedDate <= toEnd)
+            .AsNoTracking().ToListAsync();
+
+        foreach (var vca in periodVcApplied)
+            lines.Add(new StatementLineDto
+            {
+                Date        = vca.AppliedDate,
+                Type        = "Credit Applied",
+                Reference   = vca.VendorCredit.CreditNumber,
+                Description = $"Vendor credit applied to {vca.Bill.BillNumber}",
+                Credit      = vca.Amount,
+            });
+
+        lines = lines.OrderBy(l => l.Date).ThenBy(l => l.Type).ToList();
+        var running = openingBalance;
+        foreach (var line in lines)
+        {
+            running += (line.Debit ?? 0) - (line.Credit ?? 0);
+            line.RunningBalance = running;
+        }
+
+        return new VendorStatementDto
+        {
+            VendorId       = vendorId,
+            VendorName     = vendor.CompanyName,
+            CompanyName    = companyName,
+            From           = from,
+            To             = to,
+            OpeningBalance = openingBalance,
+            Lines          = lines,
+            ClosingBalance = running,
+        };
+    }
+
     /// <summary>
     /// Looks up the company name by ID for report headers and AI prompt injection.
     /// Falls back to "Your Company" if the record is not found.