Esses são os termos usados numa grande firma de auditoria para a qual eu trabalho. "Fixed assets" também é usado para imobilizado

Segundo Danilo Nogueira:

"Ativo fixo and ativo permanente

Then, of course we have the blessed ativo permanente. This dates back to the Business Corporation Act of '76 and is not the same as ativo fixo. I have often had a chance to deal with this, which in fact constitutes one of my favorite translation issues, but I can not resist the temptation of coming back to it once more.

Ativo fixo reflects what used to be called fixed assets and is now referred as property, plant and equipment, although nine out of ten CPAs will refer to fixed assets when they have reason to believe nobody is listening. Property, plant and equipment applies to industrial companies, as you know. Service enterprises, being devoid of plants, have something that usually goes by the name of premises and equipment. But ativo permanente includes both imobilizado (fixed assets), investimentos (fixed investments) and ativo diferido (deferred charges). I usually cross my fingers and translate ativo permanente as "permanent" assets and pray that the general layout of the balance sheet will help a foreign reader understand what it is. In fact, under Law 6404/76, permanente reflects assets subject to correção monetária (indexation). That, of course, does not help me very much."

http://www.accurapid.com/journal/11money.htm