Why is cost centre disabled on an article line?

The cost centre field only becomes selectable on an article line when all of the following apply:

• You've selected Uses cost centres under Settings - Company settings - Accounting details.
• You've selected a customer on the document.
• The line has an article selected, and the article has account coding configured. Lines without an article, in other words free-text amounts, can never get a cost centre - the field is only available on article lines.
• There's an active financial year that covers the invoice date.
• The account the line is posted to has the checkbox Uses cost centres on the account selected in the chart of accounts.

The last condition is the most common reason the field is greyed out even though you use cost centres. Which account a line is posted to depends, among other things, on the customer's country, VAT registration number, and whether the customer is a private individual or a company. This means the same article can give a selectable cost centre for one customer but a disabled one for another, if the lines are posted to different accounts.

Income and expense accounts have cost centres pre-enabled by default, while asset and liability accounts don't. If you want to post cost centres on such an account, you need to enable it on that specific account. Read more in the Add cost centres section.

Cost centre isn't saved on the article. If you've selected a cost centre in the document header, it's automatically filled in on all lines where the field is selectable, which can look like it comes from the article - but it doesn't.

Read more about how to get started with cost centres in the topic How do I start using cost centres?.