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fix(#66): prevent inclusive tax double-counting on order totals and discounts #67

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Merged
ARCHITVARMA15 merged 2 commits into from
Jul 8, 2026
+178 −24
Merged

fix(#66): prevent inclusive tax double-counting on order totals and discounts #67

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f32b11f
fix(#66): prevent inclusive tax double-counting on order discount
ARCHITVARMA15 Jul 8, 2026
cdeabc0
tax bug improvised
ARCHITVARMA15 Jul 8, 2026
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16 changes: 14 additions & 2 deletions main/routes/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -147,9 +147,13 @@ export function registerRoutes(app: Express): void {
.all(orderId) as any[];
let subtotal = 0;
let totalTax = 0;
let exclusiveTax = 0;
for (const i of activeItems) {
subtotal += i.subtotal || 0;
totalTax += i.tax_amount || 0;
if (i.tax_type !== 'inclusive') {
exclusiveTax += i.tax_amount || 0;
}
}

// BUG #13 FIX: Preserve order-level discount (scale percentage proportionally)
Expand All @@ -165,13 +169,15 @@ export function registerRoutes(app: Express): void {

const discountedSubtotal = Math.max(0, subtotal - newDiscountAmount);
let newTaxAmount = totalTax;
let newExclusiveTax = exclusiveTax;
if (newDiscountAmount > 0 && subtotal > 0) {
const taxRatio = discountedSubtotal / subtotal;
newTaxAmount = Math.round(totalTax * taxRatio * 100) / 100;
newExclusiveTax = Math.round(exclusiveTax * taxRatio * 100) / 100;
}

// BUG #5 FIX: Correct round-off formula; BUG #24 FIX: include delivery_charge (was missing, causing total mismatch with bill generation)
const preRoundTotal = discountedSubtotal + newTaxAmount + (order.delivery_charge || 0) + (order.packaging_charge || 0);
const preRoundTotal = discountedSubtotal + newExclusiveTax + (order.delivery_charge || 0) + (order.packaging_charge || 0);
const roundOff = Math.round(preRoundTotal) - preRoundTotal;
const total = Math.round(preRoundTotal);

Expand Down Expand Up @@ -248,9 +254,13 @@ export function registerRoutes(app: Express): void {
.all(orderId) as any[];
let subtotal = 0;
let totalTax = 0;
let exclusiveTax = 0;
for (const i of activeItems) {
subtotal += i.subtotal || 0;
totalTax += i.tax_amount || 0;
if (i.tax_type !== 'inclusive') {
exclusiveTax += i.tax_amount || 0;
}
}

// BUG #13 FIX: Preserve order-level discount (scale percentage proportionally)
Expand All @@ -266,13 +276,15 @@ export function registerRoutes(app: Express): void {

const discountedSubtotal = Math.max(0, subtotal - newDiscountAmount);
let newTaxAmount = totalTax;
let newExclusiveTax = exclusiveTax;
if (newDiscountAmount > 0 && subtotal > 0) {
const taxRatio = discountedSubtotal / subtotal;
newTaxAmount = Math.round(totalTax * taxRatio * 100) / 100;
newExclusiveTax = Math.round(exclusiveTax * taxRatio * 100) / 100;
}

// BUG #5 FIX: Correct round-off formula; BUG #24 FIX: include delivery_charge (was missing, causing total mismatch with bill generation)
const preRoundTotal = discountedSubtotal + newTaxAmount + (order.delivery_charge || 0) + (order.packaging_charge || 0);
const preRoundTotal = discountedSubtotal + newExclusiveTax + (order.delivery_charge || 0) + (order.packaging_charge || 0);
const roundOff = Math.round(preRoundTotal) - preRoundTotal;
const total = Math.round(preRoundTotal);

Expand Down
40 changes: 31 additions & 9 deletions main/routes/orders.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,7 @@ router.post('/', requireRole('owner', 'manager', 'cashier', 'waiter'), (req: Req

let subtotal = 0;
let totalTax = 0;
let exclusiveTax = 0;
const allTaxBreakdowns: any[] = [];

const insertItem = db.prepare(`
Expand Down Expand Up @@ -208,11 +209,14 @@ router.post('/', requireRole('owner', 'manager', 'cashier', 'waiter'), (req: Req
const taxResult = calculateItemTax(tenantInfo, product, itemSubtotal, customer);

totalTax += taxResult.tax_amount;
if (taxResult.tax_type !== 'inclusive') {
exclusiveTax += taxResult.tax_amount;
}
if (taxResult.tax_breakdown) {
allTaxBreakdowns.push(taxResult.tax_breakdown);
}

const itemTotal = itemSubtotal + taxResult.tax_amount;
const itemTotal = itemSubtotal + (taxResult.tax_type === 'inclusive' ? 0 : taxResult.tax_amount);
subtotal += itemSubtotal;

insertItem.run(
Expand All @@ -231,7 +235,7 @@ router.post('/', requireRole('owner', 'manager', 'cashier', 'waiter'), (req: Req
}
}

const preRoundTotal = subtotal + totalTax + (delivery_charge || 0) + (packaging_charge || 0);
const preRoundTotal = subtotal + exclusiveTax + (delivery_charge || 0) + (packaging_charge || 0);
const total = Math.round(preRoundTotal);
const roundOff = total - preRoundTotal;

Expand Down Expand Up @@ -348,7 +352,7 @@ router.post('/:id/items', requireRole('owner', 'manager', 'cashier', 'waiter'),
itemSubtotal = Math.max(0, itemSubtotal - itemDiscount);

const taxResult = calculateItemTax(tenantInfo, product, itemSubtotal, customer);
const itemTotal = itemSubtotal + taxResult.tax_amount;
const itemTotal = itemSubtotal + (taxResult.tax_type === 'inclusive' ? 0 : taxResult.tax_amount);

insertItem.run(
req.params.id, product.id, product.name, product.sku, unitPrice, quantity,
Expand All @@ -370,15 +374,19 @@ router.post('/:id/items', requireRole('owner', 'manager', 'cashier', 'waiter'),
const activeItems = db.prepare("SELECT * FROM order_items WHERE order_id = ? AND status != 'cancelled'").all(req.params.id) as any[];
let subtotal = 0;
let totalTax = 0;
let exclusiveTax = 0;
const allTaxBreakdowns: any[] = [];
for (const item of activeItems) {
subtotal += item.subtotal;
totalTax += item.tax_amount;
if (item.tax_type !== 'inclusive') {
exclusiveTax += item.tax_amount;
}
if (item.tax_breakdown) {
try {
const breakdown = JSON.parse(item.tax_breakdown);
if (Array.isArray(breakdown)) allTaxBreakdowns.push(breakdown);
} catch {}
} catch { }
}
}

Expand All @@ -395,12 +403,14 @@ router.post('/:id/items', requireRole('owner', 'manager', 'cashier', 'waiter'),

const discountedSubtotal = Math.max(0, subtotal - newDiscountAmount);
let newTaxAmount = totalTax;
let newExclusiveTax = exclusiveTax;
if (newDiscountAmount > 0 && subtotal > 0) {
const taxRatio = discountedSubtotal / subtotal;
newTaxAmount = Math.round(totalTax * taxRatio * 100) / 100;
newExclusiveTax = Math.round(exclusiveTax * taxRatio * 100) / 100;
}

const preRoundTotal = discountedSubtotal + newTaxAmount + ((order as any).delivery_charge || 0) + ((order as any).packaging_charge || 0);
const preRoundTotal = discountedSubtotal + newExclusiveTax + ((order as any).delivery_charge || 0) + ((order as any).packaging_charge || 0);
const total = Math.round(preRoundTotal);
const roundOff = total - preRoundTotal;

Expand Down Expand Up @@ -689,18 +699,24 @@ router.patch('/:id/discount', requireRole('owner', 'manager'), (req: Request, re
// reduction each time this endpoint is called.
const activeItems = db.prepare("SELECT * FROM order_items WHERE order_id = ? AND status != 'cancelled'").all(req.params.id) as any[];
let freshTax = 0;
let exclusiveTax = 0;
for (const item of activeItems) {
freshTax += item.tax_amount || 0;
if (item.tax_type !== 'inclusive') {
exclusiveTax += item.tax_amount || 0;
}
}
let newTaxAmount = freshTax;
let newExclusiveTax = exclusiveTax;
if (discountAmount > 0 && order.subtotal > 0) {
const discountedSubtotal = Math.max(0, order.subtotal - discountAmount);
const taxRatio = discountedSubtotal / order.subtotal;
newTaxAmount = Math.round(freshTax * taxRatio * 100) / 100;
newExclusiveTax = Math.round(exclusiveTax * taxRatio * 100) / 100;
}

const discountedSubtotal = Math.max(0, order.subtotal - discountAmount);
const preRoundTotal = discountedSubtotal + newTaxAmount + (order.packaging_charge || 0) + (order.delivery_charge || 0);
const preRoundTotal = discountedSubtotal + newExclusiveTax + (order.packaging_charge || 0) + (order.delivery_charge || 0);
const newTotal = Math.round(preRoundTotal);
const roundOff = newTotal - preRoundTotal;

Expand Down Expand Up @@ -826,7 +842,7 @@ router.patch('/:id/items/:itemId/discount', requireRole('owner', 'manager'), (re
addonTotal += (addon.price || 0) * item.quantity;
}
}
} catch {}
} catch { }
}
const itemBaseTotal = item.unit_price * item.quantity + addonTotal;

Expand Down Expand Up @@ -855,7 +871,7 @@ router.patch('/:id/items/:itemId/discount', requireRole('owner', 'manager'), (re
const newTaxAmount = taxResult.tax_amount;
const newTaxBreakdown = taxResult.tax_breakdown;

const newTotal = newSubtotal + newTaxAmount;
const newTotal = newSubtotal + (taxResult.tax_type === 'inclusive' ? 0 : newTaxAmount);

// Update item with recalculated tax
db.prepare(`
Expand All @@ -867,9 +883,13 @@ router.patch('/:id/items/:itemId/discount', requireRole('owner', 'manager'), (re
const allItems = db.prepare('SELECT * FROM order_items WHERE order_id = ?').all(req.params.id) as any[];
let orderSubtotal = 0;
let orderTax = 0;
let exclusiveOrderTax = 0;
for (const i of allItems) {
orderSubtotal += i.subtotal;
orderTax += i.tax_amount;
if (i.tax_type !== 'inclusive') {
exclusiveOrderTax += i.tax_amount;
}
}

// Recalculate order-level discount proportionally on new subtotal
Expand All @@ -883,12 +903,14 @@ router.patch('/:id/items/:itemId/discount', requireRole('owner', 'manager'), (re
// Recalculate tax on discounted subtotal
const discountedSubtotal = Math.max(0, orderSubtotal - newOrderDiscount);
let newOrderTax = orderTax;
let newExclusiveOrderTax = exclusiveOrderTax;
if (newOrderDiscount > 0 && orderSubtotal > 0) {
const taxRatio = discountedSubtotal / orderSubtotal;
newOrderTax = Math.round(orderTax * taxRatio * 100) / 100;
newExclusiveOrderTax = Math.round(exclusiveOrderTax * taxRatio * 100) / 100;
}

const preRoundTotal = discountedSubtotal + newOrderTax + (order.packaging_charge || 0) + (order.delivery_charge || 0);
const preRoundTotal = discountedSubtotal + newExclusiveOrderTax + (order.packaging_charge || 0) + (order.delivery_charge || 0);
const orderTotal = Math.round(preRoundTotal);
const roundOff = orderTotal - preRoundTotal;

Expand Down
23 changes: 10 additions & 13 deletions package-lock.json
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5 changes: 5 additions & 0 deletions temp-tax-test.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
const { calculateItemTax } = require('./tests/helpers/test-setup'); // wait, calculateItemTax isn't exported from test-setup
const fs = require('fs');

const taxCode = fs.readFileSync('./main/services/tax.ts', 'utf8');
console.log(taxCode.includes('calculateItemTax'));
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