Modal verbs, when used with their subjective meaning, refer mostly to the present time.
| Examples | time |
| Paul muss zu Hause sein. | present |
| Paul soll zu Hause sein. |
When, however, the hypothesis or the reported statement of someone refer to the past, the modal verb is combined with a perfect infinitive (Infinitiv II).
| Examples |
present
|
past
|
|
Paul muss zu Hause
|
sein
|
gewesen sein
|
|
Paul soll zu Hause
|
sein
|
gewesen sein
|
If the hypothesis or the reported statement are made in the past, the modal verb is in the Präteritum and is connected either with a present infinitive (simultaneity) or a perfect infinitive (anteriority). Under no circumstances is the modal verb in the present perfect, past perfect or in the future tenses.