Learn Swedish: Han har noterat att företaget genomfört en bedömning. - He has noted that the company has carried out an assessment.

This is a classic example of dropping the 'have' (ha-bortfall). In written and formal Swedish, you can omit the auxiliary verbs har and hade in subordinate clauses. Since att företaget genomfört en bedömning is a subordinate clause, the har is understood but left out.

Why isn't the har dropped in Han har noterat as well?

The rule for dropping har or hade only applies to subordinate clauses. These are dependent clauses that usually start with words like att, om, or eftersom. Han har noterat is the main clause, so the auxiliary verb must remain.

How do I know whether genomfört means 'has carried out' or 'had carried out'?

Context tells you! You look at the tense of the main clause. Since the main clause is in the present perfect (har noterat), the missing word in the subordinate clause is naturally har. If the main clause were in the past tense (noterade), the missing word would be hade.

Can I split genomfört into fört genom?