PHP FacturaE supports both line-level discounts and invoice-level general discounts and charges. This guide covers invoice-level adjustments that apply to the total invoice amount.
General Discounts
Apply discounts at the invoice level using the generalDiscount() method:
use PhpFacturae\Invoice;
$invoice = Invoice::create('FAC-001')
->seller($seller)
->buyer($buyer)
->line('Product A', price: 100.00, vat: 21)
->line('Product B', price: 200.00, vat: 21)
->generalDiscount('VIP customer discount', amount: 50.00)
->toXml();
General discounts are applied to the gross invoice total before tax calculations, reducing the taxable base.
General Charges
Add additional charges at the invoice level using the generalCharge() method:
$invoice = Invoice::create('FAC-002')
->seller($seller)
->buyer($buyer)
->line('Service', price: 500.00, vat: 21)
->generalCharge('Shipping costs', amount: 15.00)
->toXml();
Charges increase the taxable base, so taxes are calculated on the total including charges.
Fixed Amount vs Percentage Rate
You can specify discounts and charges either as a fixed amount or as a percentage rate.
Fixed Amount
// Discount of €50
->generalDiscount('Early payment discount', amount: 50.00)
// Charge of €15
->generalCharge('Handling fee', amount: 15.00)
Percentage Rate
// 10% discount on gross total
->generalDiscount('Volume discount', rate: 10)
// 5% surcharge
->generalCharge('Rush order fee', rate: 5)
Calculate the gross total of all invoice lines
Apply the rate percentage to the gross total
The calculated amount is used as the discount/charge
Adjust the taxable base accordingly
Calculate taxes on the adjusted base
Multiple Discounts and Charges
You can apply multiple discounts and charges to the same invoice:
$invoice = Invoice::create('FAC-003')
->seller($seller)
->buyer($buyer)
->line('Consulting', price: 1000.00, vat: 21)
->line('Materials', price: 300.00, vat: 21)
// Apply multiple discounts
->generalDiscount('Early payment', rate: 5)
->generalDiscount('Loyalty program', amount: 25.00)
// Add charges
->generalCharge('Shipping', amount: 20.00)
->generalCharge('Insurance', rate: 2)
->toXml();
When using both rate and amount parameters together, the amount parameter takes precedence. Only specify one per discount/charge.
How Discounts Affect Total Calculation
Here’s how general discounts and charges are applied:
// Example calculation
$invoice = Invoice::create('FAC-004')
->line('Item 1', price: 100.00, vat: 21) // €100
->line('Item 2', price: 200.00, vat: 21) // €200
->generalDiscount('Discount', amount: 30.00)
->generalCharge('Shipping', amount: 10.00);
// Gross total: €300.00
// After discount: €300.00 - €30.00 = €270.00
// After charge: €270.00 + €10.00 = €280.00
// Taxable base: €280.00
// VAT (21%): €58.80
// Invoice total: €338.80
Complete Example
use PhpFacturae\Invoice;
use PhpFacturae\Party;
$seller = Party::company('B12345678', 'Mi Empresa S.L.')
->address('Calle Mayor 1', '28001', 'Madrid', 'Madrid');
$buyer = Party::company('A87654321', 'Cliente Premium S.A.')
->address('Gran Via 10', '28013', 'Madrid', 'Madrid');
$invoice = Invoice::create('FAC-2024-0015')
->series('A')
->date('2024-03-15')
->seller($seller)
->buyer($buyer)
// Invoice lines
->line('Web development', price: 2000.00, vat: 21)
->line('Hosting (annual)', price: 120.00, vat: 21)
->line('SSL certificate', price: 50.00, vat: 21)
// Apply 10% early payment discount
->generalDiscount('10% early payment discount', rate: 10)
// Add shipping charge
->generalCharge('Express delivery', amount: 25.00)
// Payment terms
->transferPayment(
iban: 'ES91 2100 0418 4502 0005 1332',
dueDate: '2024-04-15'
)
->toXml();
// Calculation breakdown:
// Lines total: €2,170.00
// 10% discount: -€217.00
// Shipping: +€25.00
// Taxable base: €1,978.00
// VAT 21%: €415.38
// Total: €2,393.38
Method Reference
Both methods are defined in Invoice.php:
generalDiscount()
public function generalDiscount(
string $reason,
?float $rate = null,
?float $amount = null
): self
Invoice.php:358
generalCharge()
public function generalCharge(
string $reason,
?float $rate = null,
?float $amount = null
): self
Invoice.php:374
Parameters
- reason (required): Description of the discount/charge
- rate: Percentage rate to apply (e.g.,
10 for 10%)
- amount: Fixed amount in invoice currency
Provide descriptive reasons for discounts and charges. These appear on the invoice and help explain the adjustments to your customers and tax authorities.
Line-Level Discounts
For discounts on individual lines, use the discount parameter in the line() method:
->line(
description: 'Product with line discount',
price: 100.00,
vat: 21,
discount: 10 // 10% discount on this line only
)
Common Scenarios
Early Payment Discount
->generalDiscount('Early payment discount - 5%', rate: 5)
Volume-Based Discount
->generalDiscount('Volume discount - orders over €1000', amount: 100.00)
Shipping and Handling
->generalCharge('Shipping and handling', amount: 15.50)
Insurance Fee
->generalCharge('Insurance fee', rate: 2)
Combined Discounts
->generalDiscount('Seasonal discount', rate: 10)
->generalDiscount('Loyalty points redemption', amount: 50.00)
Best Practices
Use clear, descriptive reasons that explain why the discount or charge was applied.
Use Rates for Proportional Adjustments
When the adjustment should scale with the invoice amount, use rates instead of fixed amounts.
Document Special Arrangements
For negotiated discounts, reference the agreement in the description.
Always verify that the final total matches your expectations, especially with multiple adjustments.
// From Invoice.php:52-55
private array $generalDiscounts = [];
private array $generalCharges = [];
// Each entry has the structure:
[
'reason' => 'Discount description',
'rate' => 10.0, // optional
'amount' => 50.0
]