在建设施工合同中，“背靠背”条款一般是指建设工程的总包方与分包方约定，以业主付款作为其向分包方支付相应工程款为前提的条款，若业主未付款，总包方可以该条款抗辩分包方的付款请求权。“背靠背”条款在合同中的表现形式不一，常见的两种形式是按业主付款期限与按业主的付款比例支付工程款。

“背靠背”条款起源于西方的 “pay-if-paid”、“pay-when-paid”条款。 “pay-if-paid”自上个世纪80 年代始逐渐得以使用，1995年11月，弗吉尼亚州最高法院首次使用“pay-when-paid” 条款，并且表明只要合同内容清楚并明确表达了双方当事人的意思，那么即为有。在中国学术界，将 “pay-if-paid”以及 “pay-when-paid” 视为等同，有些学者将其译为 “业主先期支付条款”，通常翻译为 “背靠背”条款”。

关于pay-if-paid条款 和 pay-when-paid条款，可参考如下英文释义：Pay-if-Paid ("PIP") and Pay-when-Paid ("PWP") clauses are contractual conditional- payment provisions primarily intended to shift risk of loss related to non-payment downward to lower-tier subcontractors. Jurisdictional enforceability of PIPs vary wildly from almost complete blind recognition to absolute legislative and/or judicial prohibitions. PIPs are customarily viewed extremely disfavorably; as the transfer risk downward to the lower-tiered subcontractors is usually viewed as inequitable and patently unfair. In contrast, PWPs are viewed, not so much as a legal tool for non-payment, but as a timing instrument for the payment of downstream-subcontractor, within a reasonable timeframe after completion and as a traditionally-accepted means of risk sharing. These clauses require the careful analysis of two distinct, yet important, competing legal theories: contract vs. equity.

PIP describes a clause in which the upstream contractor's (usually the Prime/GC) payment obligation(s) to pay downstream subcontractors' claims is/are triggered ONLY, if and after, the receipt of payment, in full, from a higher-tiered contractor or Owner, for the lower-tiered subs' work. PIP clauses are customarily viewed as HIGHLY disfavored and EXTREMELY inequitable. Generally, this is because PIP clauses are an instrument to pass risk downward through the subcontracting levels, which are generally the entities/individuals most likely to suffer the greatest from such risk increase (e.g. the "too big to fail" analogy: the socialization of risk downward across all levels of subcontractors). There is the perception that PIP clauses unfairly/unreasonably shift credit risk to downstream subs, who are most usually not in privity. The obligation of Prime/GC to pay downstream subs is triggered ONLY after the Prime/GC's receipt of payment, in full, from Owner for the relevant work billed to Owner from Prime/GC, for work which included the work performed by the lower-tiered subs.

PWP clauses establish the required payment timeliness of upstream contractor's payment obligation to pay lower-tiered subcontractors is triggered only after the upstream contractor is paid. 5 The trigger for obligation will typically have timing provisions associated with the clauses. PWP clauses normally lack explicit language requiring the Prime/GC's receipt of payment as a condition precedent for the payment of the relevant lower-tiered subcontractor's work. The underlying theory behind PWP clauses is to establish and/or increase protections for higher-tiered contractors against claims by lower-tiered subs. PWP clauses normally have explicit "timing provisions" which outline the relevant payment trigger(s). If the timeliness directives are absent, "murky", or ambiguous; anticipate the upper-tier payment obligation(s) downstream due and payable within a reasonable time after such lower-tiered subs' work is completed. PWP clauses will fall into one of two categories: A) Clause which does not require the Prime/GC/higher-tiered sub to receive payment, in full, for the relevant lower-tiered subs' work before payment for same, as an express condition precedent; OR B) an intended PIP which the relevant payment clause(s)/term(s) is/are "murky" and/or ambiguous which provides the Court with an "out" (i.e. not to enforce the intended PIP).