Do I have to wear niqab in front of in-laws and cousins?
It follows the ruling on niqab itself. Scholars who require or recommend covering do not treat relatives differently — a brother-in-law or cousin is not a maḥram. Since this site does not settle whether niqab is obligatory, it does not settle this either.
The answer is conditional, and the condition is unsettled
Scholars who hold covering the face obligatory or recommended do not divide unrelated men into categories. For them a man is either maḥram or ajnabī, and family connection does not create a third class. Brothers-in-law, cousins and step-siblings are ajnabī.
The consequence is conditional, and the wording matters: if the niqab is obligatory, then it is obligatory before in-laws too.
This site does not settle whether niqab is obligatory, with that judgement suspended throughout, so this page cannot resolve into a plain yes. What it establishes is narrower: whatever the ruling on niqab is, it applies to these relatives as it does to any other unrelated man. Family closeness is not itself an exemption.
Shaykh Muqbil al-Wādiʿī (d. 1422 H), asked whether a woman may lift her niqab before a cousin, answered that since marriage to him is permissible, she may not — the concession belongs only to men permanently prohibited from marrying her.
A middle position
Al-Mawdūdī takes a graded view: non-maḥram relatives are neither the same as maḥram nor necessarily to be treated like distant strangers. The degree of covering is judged by how close the relationship is, by age, by whether the households live together or apart, and by the actual nature of the relationship.
This assessment is worth quoting accurately: al-Mawdūdī's reasoning is judged weak, but the view itself worth considering. Those are not the same judgement, and a summary should not collapse them into endorsement.
The closing note
This section ends not with a ruling but with a request, and it sets the tone this site tries to keep.
The closing request is that Muslims not narrow the matter to the point of condemning women who do not veil before particular relatives, accusing them of being selective, inconsistent, or hypocritical. The reasoning given is practical: such treatment only drives women away from the practice altogether.
And the closing principle is one of accommodation rather than all-or-nothing: what cannot be attained in full is not abandoned in the greater part.
If one is able, the better course is preferred; but if one is not able, then — what cannot be attained in full is not abandoned in the greater part.
Check your understanding
According to the note, why do brothers-in-law and cousins not get special treatment under the rulings that require or recommend covering the face?