Acúmulo de funções

10:31 Nov 26, 2016 

Boa solução, Teresa. Obrigado.
No glossário ficará "extra duties" e "duties beyond the contractual scope"

07:05 Nov 26, 2016 

... duties beyond the scope of work/duties beyond the scope of the post?

00:56 Nov 26, 2016 

Extra duties may be a good option. However, not extra work, as I mentioned below.
Thank you.

20:00 Nov 25, 2016 

I would use Nick's alternative suggestion of (being given/assigned) 'extra duties', which avoids any confusion with overtime.

The Trades Union Congress (TUC) in the UK uses that term to describe the situation you are referring to.

https://worksmart.org.uk/work-rights/pay-and-contracts/job-t...

15:49 Nov 25, 2016 

This is a very specific thing, and there must be a term for it in English, as the same thing may happen there.
The employer hires a person to be a receptionist. Then they tell her she will also take care of the traveling (booking tickets, hotels, etc.). Then they tell her she will coordinate the drivers' schedule, too. These two last functions are not in her labor agreement.
This is "acúmulo de funções" in this context. It's not the employee's choice. The employer is the one breaching the law.
So, it's not ilegally taking duties or holding jobs, as this would be a breach by the employee. It could be extra work, but that would cause confusion with overtime or een with extra work within one's role and expected function.
So Salvador's suggestion is the closest one so far.

08:22 Nov 25, 2016 

holding two offices?