How to use term describe `out of scope` job, but it is a company tasks

You may call such jobs voluntary.

ODO:

voluntary ADJECTIVE

2 Working, done, or maintained without payment.

‘The school cleaner volunteers have been protesting for about a month outside the gates of the legislature, demanding payment for voluntary work offered since 1997.’

Also, the phrase pro bono is used (typically in the legal profession).

ODO:

pro bono

ADVERB & ADJECTIVE [North American]
Denoting work undertaken without charge, especially legal work for a client on low income.

‘Most of the many hours he works each day are pro bono to help the administration with its policy on Iraq.’