---
title: Line item calculator
slug: commerce-connect-14/docs/calculating-orders-line-item-calculator
docTags: 
createdAt: 2026-07-23T10:25:34.040Z
---

## Extended price

Calculates the price including order-level discount amount (spread over all line items in the shipment) *and* any line item discount amount.

```csharp
public void GetExtendedPrice(ILineItem lineItem, Currency currency, ILineItemCalculator lineItemCalculator)
          {
            var extendedPrice = lineItemCalculator.GetExtendedPrice(lineItem, currency);
            Debug.WriteLine("Extended price for '{0}': {1}", lineItem.Code, extendedPrice);
          }
```

## Discounted price

Only calculates the price with the "line item discount amount," that is, the discount for a specific line item.

```csharp
public void GetDiscountedPrice(ILineItem lineItem, Currency currency, ILineItemCalculator lineItemCalculator)
          {
            var discoutedPrice = lineItemCalculator.GetDiscountedPrice(lineItem, currency);
            Debug.WriteLine("Discounted price for '{0}': {1}", lineItem.Code, discountedPrice);
          }
```

## Line item price

Calculates the line item price, which includes a line item's extended price and discounted price.

```csharp
public void GetLineItemPrices(ILineItem lineItem, Currency currency, ILineItemCalculator lineItemCalculator)
          {
            var lineItemdPrices = lineItemCalculator.GetLineItemPrices(lineItem, currency);
            Debug.WriteLine("Extended price for '{0}': {1}", lineItem.Code, lineItemdPrices.ExtendedPrice);
            Debug.WriteLine("Discounted price for '{0}': {1}", lineItem.Code, lineItemdPrices.DiscountedPrice);
          }
```

## Sales tax

Calculates a line item's sales tax.

```csharp
public void GetSalesTax(ILineItem lineItem, IMarket market, Currency currency, IOrderAddress shippingAddress, ILineItemCalculator lineItemCalculator)
          {
            var salesTax = lineItemCalculator.GetSalesTax(lineItem, market, currency, shippingAddress);
            Debug.WriteLine("Sales tax for '{0}': {1}", lineItem.Code, salesTax);
          }
```

Calculates line items' sales tax.

```csharp
public Money GetSalesTax(IEnumerable<ILineItem> lineitems, IMarket market, Currency currency, IOrderAddress shippingAddress, ILineItemCalculator lineItemCalculator)
          {
            return lineItemCalculator.GetSalesTax(lineitems, market, shippingAddress, currency);
          }
```

## Change the default calculation

By inheriting from the default implementation of the interface, `DefaultLineItemCalculator`, you can override the extended price and sales tax calculations. To change the calculation of a line item's extended price, override the `CalculateExtendedPrice` method. To change the calculation of line item's sales tax, override the `CalculateSalesTax` method.

```csharp
public class LineItemCalculatorSample : DefaultLineItemCalculator
      {
        protected override Money CalculateExtendedPrice(ILineItem lineItem, Currency currency)
          {
            return new Money(0, currency);
          }
    
        protected override Money CalculateSalesTax(ILineItem lineItem, IMarket market, Currency currency, IOrderAddress shippingAddress)
          {
            return new Money(0, currency);
          }
      }
```

## Change the default validation

The default implementation validates that the extended price and sales tax are not negative after the calculation. To change the behavior, override the `ValidateExtendedPrice` and `ValidateSalesTax` methods.

```csharp
public class LineItemCalculatorSample : DefaultLineItemCalculator
      {
        protected override void ValidateExtendedPrice(Money money)
          {
            if (money.Amount <= 0)
              {
                throw new ValidationException("Extended price must be greater than 0");
              }
          }
    
        protected override void ValidateSalesTax(Money money)
          {
            if (money.Amount <= 0)
              {
                throw new ValidationException("Sales tax must be greater than 0");
              }
          }
      }
```