> For the complete documentation index, see [llms.txt](https://helpwith.salesorder.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://helpwith.salesorder.com/products-services/items-which-ones/calculation-items.md).

# 'Calculation' Items

{% hint style="info" %}
Use the 'sub total' element to add the balances of a series of preceding line items and apply a calculation item.  The sub total item is added from the Item selector.
{% endhint %}

### Charge Item <a href="#i9y131ggmpdv" id="i9y131ggmpdv"></a>

This Item can be used to add an arbitrary charge as a percentage of the preceding line Item i.e. a sub-total. It can also represent a fixed charge.

The Charge Item can be used to bill for the supply of goods or services by a third party. Use the Purchasing tab to set the costs and supply details.

#### Accounting <a href="#o5eg9166g14k" id="o5eg9166g14k"></a>

The Charge item can post to an Income and an Expense Account.

### Discount Item <a href="#g784odjhgt8z" id="g784odjhgt8z"></a>

This Item is used to apply a discount to the preceding line Item i.e. a sub-total. See ‘[Discounts](/sales/sales-orders/discounts.md)’.

#### Accounting <a href="#j12znjvksldp" id="j12znjvksldp"></a>

The Discount Item can post to an Income or an Expense Account.

### Mark up Item <a href="#fohxlws9g9iq" id="fohxlws9g9iq"></a>

The Markup Item is used to apply a markup to the preceding line Item of a fixed amount or a percentage.

#### Accounting <a href="#cq7aubd1g3cx" id="cq7aubd1g3cx"></a>

The Mark up Item posts to an Income account.