Can the first wife claim jointly acquired matrimonial property (harta sepencarian) when her husband takes another wife?

Yes. The court that grants polygyny permission (or orders the marriage to be registered) may, on the application of any party, order the division of assets acquired jointly during the marriage (Act 303 s.23(9)(b) in the Federal Territories; Selangor Enactment 2003 s.23(10)(b)). The aim is to protect the first wife's contribution before there is a new wife. Section numbers and wording may differ in other states' enactments, so check your state's enactment or ask a Syariah lawyer. Jointly acquired matrimonial property (harta sepencarian) can also be claimed on divorce (Act 303 s.122) or death. Gather evidence of direct and indirect contributions, such as instalment payments and caring for the home and children. See women's rights and the state-by-state guide.