Make cash refunds reverse the sale instead of re-opening AR

Audit finding 9a: a cash refund posted DR AR (control up) while the customer subledger went down — opposite directions, guaranteeing AR drift. Per the chosen model, a cash refund now *reverses the sale*: DR Sales Returns (revenue portion) + DR Sales Tax Payable (tax portion) / CR Bank, with the customer AR balance left untouched (the invoice stays paid; the sale is contra'd). - New 4960 "Sales Returns & Allowances" contra-revenue account (seed + self-heal). - Tax/revenue split centralized in Core RefundAllocation.Split so the posting and both reporting recomputes compute it identically (a mismatch would unbalance the trial balance). - InvoicesController IssueRefund/CancelRefund: new posting + reversal; no AR/ customer-balance change. - LedgerService (per-account + prior balance): refunds debit Sales Returns + Sales Tax, no longer debit AR; bank credit unchanged. - FinancialReportService: trial balance, balance sheet (retained earnings + tax liability), and P&L (contra-revenue line) all updated to match. Store-credit refunds are excluded everywhere (they post via CreditMemo, not the GL — 9b). Verified: $108 refund (incl. $8 tax) -> bank -100... checks: assets -108 = liabilities -8 + equity -100. New tests cover the split invariant and the ledger postings. Build clean; 283 unit tests pass. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-18 19:58:42 -04:00
parent f54b945053
commit 2a82a1d34b
7 changed files with 288 additions and 51 deletions
@@ -509,6 +509,57 @@ public class LedgerServiceTests

    // ── Helpers ───────────────────────────────────────────────────────────

+    // ── Cash refund reverses the sale: Sales Returns + Sales Tax debited, AR untouched ──
+
+    [Fact]
+    public async Task GetAccountLedgerAsync_CashRefund_ReversesTheSale_DebitsReturnsAndTax_NotAr()
+    {
+        await using var context = CreateContext();
+
+        context.Accounts.Add(new Account { Id = 1, CompanyId = 1, AccountNumber = "1000", Name = "Checking",          AccountType = AccountType.Asset,     AccountSubType = AccountSubType.Checking,             IsActive = true });
+        context.Accounts.Add(new Account { Id = 2, CompanyId = 1, AccountNumber = "1100", Name = "AR",                AccountType = AccountType.Asset,     AccountSubType = AccountSubType.AccountsReceivable,   IsActive = true });
+        context.Accounts.Add(new Account { Id = 3, CompanyId = 1, AccountNumber = "2200", Name = "Sales Tax Payable", AccountType = AccountType.Liability, AccountSubType = AccountSubType.OtherCurrentLiability, IsActive = true });
+        context.Accounts.Add(new Account { Id = 4, CompanyId = 1, AccountNumber = "4960", Name = "Sales Returns",     AccountType = AccountType.Revenue,   AccountSubType = AccountSubType.OtherIncome,          IsActive = true });
+
+        // Invoice $108 incl. $8 tax, tax posted to account 3.
+        context.Invoices.Add(new Invoice
+        {
+            Id = 99, CompanyId = 1, InvoiceNumber = "INV-0099", CustomerId = 1,
+            Status = InvoiceStatus.Sent, InvoiceDate = InPeriod,
+            Total = 108m, TaxAmount = 8m, SalesTaxAccountId = 3
+        });
+
+        // Full cash refund of $108 paid from Checking.
+        context.Refunds.Add(new Refund
+        {
+            Id = 1, CompanyId = 1, InvoiceId = 99, Amount = 108m,
+            RefundDate = InPeriod, RefundMethod = PaymentMethod.Check, DepositAccountId = 1
+        });
+        await context.SaveChangesAsync();
+
+        var svc = CreateService(context);
+
+        // Sales Returns (4960): revenue portion debited ($100).
+        var returns = await svc.GetAccountLedgerAsync(4, PeriodStart, PeriodEnd);
+        var returnsEntry = Assert.Single(returns!.Entries, e => e.Source == "Refund");
+        Assert.Equal(100m, returnsEntry.Debit);
+        Assert.Equal(0m, returnsEntry.Credit);
+
+        // Sales Tax Payable: tax portion debited ($8), relieving the liability.
+        var tax = await svc.GetAccountLedgerAsync(3, PeriodStart, PeriodEnd);
+        var taxEntry = Assert.Single(tax!.Entries, e => e.Source == "Refund");
+        Assert.Equal(8m, taxEntry.Debit);
+
+        // Bank: full $108 credited (cash leaves).
+        var bank = await svc.GetAccountLedgerAsync(1, PeriodStart, PeriodEnd);
+        var bankEntry = Assert.Single(bank!.Entries, e => e.Source == "Refund");
+        Assert.Equal(108m, bankEntry.Credit);
+
+        // AR is no longer touched by refunds under the "reverse the sale" model.
+        var ar = await svc.GetAccountLedgerAsync(2, PeriodStart, PeriodEnd);
+        Assert.DoesNotContain(ar!.Entries, e => e.Source == "Refund");
+    }
+
    private static LedgerService CreateService(ApplicationDbContext context)
        => new LedgerService(context, Mock.Of<ILogger<LedgerService>>());

@@ -0,0 +1,22 @@
+using PowderCoating.Core.Accounting;
+
+namespace PowderCoating.UnitTests;
+
+public class RefundAllocationTests
+{
+    [Theory]
+    [InlineData(108, 8, 108, 100, 8)]   // full refund, proportional tax
+    [InlineData(54, 8, 108, 50, 4)]     // half refund → half the tax
+    [InlineData(100, 0, 100, 100, 0)]   // no tax on the invoice
+    [InlineData(100, 8, 0, 100, 0)]     // zero invoice total → all returns, no tax
+    public void Split_AllocatesTaxProportionally_AndAlwaysSumsToRefund(
+        decimal amount, decimal invoiceTax, decimal invoiceTotal, decimal expectedReturns, decimal expectedTax)
+    {
+        var (returns, tax) = RefundAllocation.Split(amount, invoiceTax, invoiceTotal);
+
+        Assert.Equal(expectedReturns, returns);
+        Assert.Equal(expectedTax, tax);
+        // Invariant: the two portions must always reconstruct the refund exactly (no penny lost).
+        Assert.Equal(amount, returns + tax);
+    }
+}