Parts-of-Speech – What Is the Tense of the Sentence ‘They Are Married’?

Married is a past participle (not a simple past) employed as an adjective. The sentence is in the present tense, marked by the present form are.

Past participles of transitive verbs are employed in passive constructions (BE + past participle), so they very readily come to be used as adjectives describing the state which is imposed by the action of the verb.

For instance, if I lost my keys yesterday, this may be expressed in the passive by saying that my keys were lost yesterday. Today (unless I find them again) I may say that my keys are lost; this is no longer a passive event but a description of my keys: they are in a 'lost' state. And when I do find my keys again I will be able to say that they are found.

Likewise, if two people marry each other we may narrate the event as a passive: Jack and Susan were married yesterday^†; but the consequence is that they are now in the 'married' state, and we say that they are married.

^† _{Lambie points out that with marry the passive version is not in present-day English an ordinary transformation of the active: they were not married by each other, but by a third party: "Jack and Susan were married by Rev. Blovious". But the passive does nonetheless give rise to expressing the state they now enjoy as married.}