You are building an approval workflow and you have reached the point where multiple people need to sign off. The default instinct is to route them one after another: person A reviews, then person B, then person C. That chain feels logical. It mirrors the way approvals work in email. But in many workflows it doubles or triples your cycle time for no good reason, because person B does not actually need to see person A's decision before making their own. The choice between sequential and parallel routing is one of the most consequential design decisions in any BPM workflow. Getting it wrong is expensive.
According to Forrester research, BPM initiatives deliver up to 50 percent productivity gains for administrative processes. A large portion of that gain comes specifically from eliminating unnecessary wait time, and sequential routing where parallel is appropriate is one of the most consistent sources of unnecessary wait.
Sequential routing means each approver acts in turn, and no approver receives the request until the previous one has completed their review. This creates a dependency chain. If approver A takes 24 hours and approver B takes 24 hours and approver C takes 24 hours, your minimum cycle time is 72 hours even if none of the reviews are dependent on each other in any meaningful way.
Parallel routing means multiple approvers receive the request simultaneously and can review independently. The workflow advances when all required approvers have acted, or when a defined quorum has acted, depending on how the completion logic is configured. If the same three approvers each take 24 hours but all review simultaneously, the cycle time is 24 hours, not 72. When the reviews are genuinely independent, this is the correct architecture.
The critical question is not which approach is simpler to configure. It is which approach matches the actual decision dependencies in your process. A workflow that uses sequential routing because the designer defaulted to it, rather than because later approvers genuinely need earlier decisions before they can act, is leaving cycle time reduction on the table.
Before routing decisions are made, map each approval stage against a dependency question: does this approver need to see the outcome of any previous approval before they can make their own decision? If the answer is no for two approvers, they are candidates for parallel routing. If the answer is yes, the dependency exists and sequential routing is correct for that pair.
In a vendor onboarding approval workflow, for example, the procurement team reviews commercial terms, the legal team reviews contract language, and the IT security team reviews vendor data practices. None of these three reviews depends on the others. All three can receive the request simultaneously and review in parallel. The workflow advances when all three have approved. This is the correct architecture, and it reduces a three-stage sequential cycle to a single parallel gate.
In a capital expenditure approval workflow, the finance controller reviews budget availability before the CFO approves the investment. The CFO needs to see that the budget check was passed before making the final authorization decision. This is a genuine dependency. Sequential routing is correct for this pair, regardless of the fact that other parts of the same workflow might benefit from parallel routing.
Sequential routing is appropriate in three specific scenarios. First, when a later approver's decision is meaningfully informed by an earlier approver's judgment and the earlier approval is a precondition for the later one. Second, when your compliance or audit requirements specify that approvals must be obtained in a defined order. Third, when the approval authority escalates with each level and a lower-level approval is required before escalating to senior management.
The cost of unnecessarily sequential routing is cycle time, and cycle time has a business cost. In procurement, it delays purchasing decisions, which delays project timelines and can trigger emergency purchasing at premium prices. In HR processes, it delays onboarding, which extends the time before new employees are productive. In compliance approvals, it creates backlogs that increase regulatory exposure. Every unnecessary sequential step is a time tax imposed on every request that flows through the workflow.
Parallel routing is appropriate when approvals are independent, when cycle time is a primary concern, and when the completion condition can be defined clearly. The most common parallel routing scenarios are specialist reviews where each reviewer brings a different domain expertise to the same request, multi-regional approvals where the same request requires sign-off from managers in different geographies who have no operational dependency on each other, and compliance reviews where multiple regulatory dimensions must be verified independently.
The most common design trap in parallel approval workflows is an ambiguous completion condition. Before configuring parallel routing, define explicitly what constitutes a completed parallel gate. Does every parallel approver need to approve, or can the workflow proceed when a majority approves? What happens if one approver rejects while others approve? What happens if one approver takes significantly longer than the others? Each of these scenarios needs a defined outcome in the workflow logic before the first request flows through it.
A second common trap is assigning too many parallel approvers to a single gate. As the number of parallel approvers increases, so does the probability that at least one is unavailable, slow, or unresponsive. Design parallel gates with the minimum number of approvers required for adequate review coverage, and include SLA enforcement with escalation for any parallel gate where one reviewer's delay can block the workflow for all other completed reviewers.
A parallel gate in BPM terminology has two components: a fork that distributes the request to multiple approvers simultaneously, and a join that waits for the defined completion condition before advancing the workflow. The join condition is the most important configuration decision. A strict join requires all parallel approvers to act. A conditional join advances when a specified number or quorum of approvers act. A first-response join advances on the first approval, which is used for escalation scenarios rather than multi-approver review scenarios.
Merge conflict risk in parallel workflows occurs when the same data field can be updated by multiple approvers independently and the workflow does not have a defined resolution logic for conflicting updates. Prevent this by designing parallel reviews as read-only assessments with a structured decision field, approval or rejection with a comments field, rather than as editable data reviews. Each approver makes a decision on the data as submitted. No approver modifies the underlying request during the parallel review phase.
Most enterprise approval workflows benefit from hybrid structures that apply sequential logic where dependencies exist and parallel logic where they do not. A procurement approval workflow might route the commercial review and the legal review in parallel, then require both to be completed before the sequential financial authorization chain begins. A new product introduction workflow might run brand compliance, regulatory review, and supply chain feasibility simultaneously, then escalate to commercial leadership sequentially once all three parallel reviews are complete.
Hybrid structures are more complex to design and document than purely sequential or purely parallel workflows, but they are also the most accurate model of how enterprise decisions actually work. The goal is to match the workflow structure to the actual decision logic, not to choose the simplest routing model and accept the performance consequences.
Gartner predicts that by 2025, 80 percent of companies using business process automation tools will use them to integrate various services and APIs. As those workflows grow in complexity, the accuracy of the approval routing architecture becomes directly linked to the operational performance of the processes they support.
Kissflow's workflow designer supports sequential, parallel, and hybrid approval structures through a visual routing interface that process owners can configure without development involvement. Parallel gates are configured by selecting the approvers who should receive the request simultaneously and defining the join condition: all must approve, a quorum must approve, or the workflow advances on first approval. Sequential chains are configured by ordering stages in the workflow designer.
SLA enforcement is configurable at each parallel gate, so individual slow approvers trigger automated reminders and escalations without blocking the workflow for approvers who have already acted. Rejection handling in parallel gates is configurable: a single rejection can halt the workflow immediately, or the workflow can collect all parallel decisions before determining the outcome. The audit trail captures every parallel review decision with timestamp, approver identity, and rationale in sequence.
For process owners building complex multi-approver workflows, Kissflow provides a testing environment where approval routing logic can be validated against simulated scenarios before deployment to production. This allows hybrid routing structures to be verified against all expected approval patterns, including partial completions, rejections, and absent approvers, before the first real request flows through the workflow.
1. What is the difference between parallel approval and concurrent approval in BPM terminology?
In most BPM platforms, parallel approval and concurrent approval describe the same thing: multiple approvers receiving a request simultaneously and reviewing it independently. Some platforms use concurrent to describe a scenario where approvers share editing access to a document simultaneously, which is a different architectural concept. When evaluating a BPM platform, ask specifically how simultaneous multi-approver review is implemented and what the join logic options are, rather than relying on the label used in the product documentation.
2. How do I decide which approvers can sign off simultaneously versus which must review in order?
Apply a single decision test to each pair of approvers in your workflow: does approver B need to see approver A's decision before they can make their own informed judgment? If yes, they are sequential. If no, they are candidates for parallel routing. Work through this test for every adjacent pair in your approval chain before finalizing the routing structure. Document the dependency rationale for each sequential pair so that future workflow updates do not inadvertently remove a genuine dependency in favor of faster cycle time.
3. What happens in a parallel approval workflow if one approver rejects and another approves?
The outcome depends on the join condition configured in the workflow. In an all-must-approve configuration, a single rejection terminates the workflow and routes the request to an exception handler or back to the requestor with the rejection reason. In a majority-approval configuration, the outcome is determined by the defined quorum logic. The important design requirement is that every possible combination of parallel approval outcomes has a defined workflow path. A parallel gate without explicit rejection handling creates an unresolved state when a mixed outcome occurs.
4. Can parallel approval workflows be configured without coding in standard BPM platforms?
In no-code and low-code BPM platforms, yes. Parallel routing is a standard workflow pattern that should be configurable through a visual designer by selecting approvers, choosing a join condition, and setting SLA windows. If your platform requires code changes to implement parallel gates, this is a significant constraint on the agility of your process design and should be factored into your BPM platform evaluation.
5. How do I handle a situation where one parallel approver is slower than all the others?
Configure an SLA window for the parallel gate with a reminder notification at a defined percentage of the window and an escalation to the slow approver's manager when the SLA expires. In the escalation notification, include the status of all other parallel approvers so the escalation recipient understands that one outstanding review is blocking the workflow. If the slow approver is systematically slower than others across multiple workflows, that is a process governance conversation, not a workflow configuration problem.
6. Is there a limit to how many parallel approvers can be included in a single BPM approval gate?
Technically, most BPM platforms can accommodate any number of parallel approvers in a single gate. Practically, the useful limit is four to six. Beyond that range, the probability of at least one approver being unavailable or slow becomes high enough that the parallel gate itself becomes a cycle time bottleneck, often longer than a well-designed sequential chain. If your process genuinely requires more than six independent approvals simultaneously, consider whether some of those reviews can be aggregated into a single specialist role.
7. How do hybrid approval structures affect the overall audit trail in a BPM system?
A well-designed BPM platform captures every approval decision in a sequential log regardless of whether the routing was sequential or parallel. In the audit trail, parallel approvals appear as independent entries with their individual timestamps, followed by the join event that records the outcome of the parallel gate. The audit trail accurately represents both the structure of the approval process and the chronological sequence in which individual decisions were recorded, which satisfies both audit and compliance documentation requirements.