Is it permissible to contract a marriage without paying the dowry, knowing that finances are tight and it will be paid later upon consummation?

The dowry is not a pillar of marriage; therefore, a marriage is valid without mentioning a dowry, and this is called nikah al-tafwid (delegated marriage) or al-tahkim (arbitrated marriage). If the contract is validly concluded, everything permissible between spouses becomes permissible for the husband and wife, even if the dowry was not specified or was deferred. There is no impediment to concluding a marriage contract without mentioning a dowry or with a deferred dowry if the woman agrees to it, because prompt payment or deferment of the dowry is her right. It is also permissible for her to waive it entirely after consummation if she is an adult of sound judgment.