Which of the following statements is correct when accounting for business combinations?

1/ Goodwill must be tested for impairment only when indicators exist

2/Provisions for future restructuring costs arising from the business combination should be recognized in applying the acquisition method

3/Goodwill must be tested at least annually for impairment

4/An impairment loss arising on full goodwill is allocated between the group and NCI in proportion to the carrying amount of their both goodwill balances