Implementing Approval Workflows in Slack: A Process-First Crawl-Walk-Run Guide for Finance

Implementing Approval Workflows in Slack

As a company scales, the informal communication that once worked for a small team starts to show cracks. A quick DM to the founder for a software subscription or a verbal OK for a payment is no longer sustainable. Time-critical payment requests get lost in crowded Slack channels, causing late fees and strained vendor relationships. Without a clear process, there is no auditable trail for approvals, which can become a significant issue during due diligence or tax checks. The goal isn’t to add bureaucracy, but to introduce a lightweight system that provides clarity, control, and a clear record of financial decisions. This guide provides a practical, phased approach for implementing finance approvals in Slack without disrupting your team's workflow.

What a Slack Approval Workflow Actually Means

A Slack approval workflow is not about creating red tape. It is a system designed for visibility, accountability, and auditability. For a growing startup, this transition becomes necessary at a clear inflection point. The need for a formal process is typically triggered when a company grows past 10 to 15 people, making it infeasible for one person to have visibility into every purchase.

Another trigger is when the company processes more than 10 to 15 approvals per week, which makes manual tracking difficult. At this volume, relying on memory or searching through DMs is inefficient and prone to error. The primary objective of a digital approval workflow is to create a durable, searchable record of who approved what, when, and why. This record is essential for maintaining accurate books under accounting standards like US GAAP or FRS 102 in the UK.

A structured process prevents the common problem of a missing auditable approval trail, which can derail due-diligence, tax, and compliance checks. It transforms scattered requests into a streamlined, predictable finance process automation that supports, rather than hinders, company growth.

Step 1: Create Your 2-Column Approval Rulebook

Before you touch any software, you need to solve the process problem. The most effective first step is creating a simple, two-column approval rulebook. This document acts as your single source of truth for spending authority, removing ambiguity and enabling team members to make decisions within defined limits. For most Pre-seed to Series B startups, a simple spreadsheet or shared document is all you need to start. You do not need a complex policy document, just a clear set of guidelines.

To build your rulebook, list your major spending categories, such as recurring software subscriptions, marketing campaigns, or contractor payments. For each category, assign a monetary threshold and a designated approver. This clarity prevents unauthorized spending and helps team leads manage their budgets effectively. What founders find actually works is keeping this rulebook simple and accessible to everyone in the company.

Here is a practical example of what this looks like:

• New software subscriptions <$250/mo: Designated Approver is the Team Lead.
• Marketing & ad spend <$1,000: Designated Approver is the Head of Marketing.
• R&D lab consumables <£500: Designated Approver is the Lead Scientist.
• E-commerce inventory purchase <$5,000: Designated Approver is the Operations Manager.
• Vendor invoice payments <$5,000: Designated Approver is the Founder/CEO.
• Any contract with a term >12 months: Designated Approver is the Founder/CEO.

This structure directly answers who has the authority to approve what and for how much. Once you have this rulebook, you have the foundation for your entire expense approval process. It will guide every subsequent step, from manual processes to full finance automation.

The Crawl-Walk-Run Approach to Slack Finance Automation

Rolling out a new process requires a phased approach to minimize disruption and encourage adoption. The Crawl-Walk-Run methodology allows your team to adapt gradually, ensuring the system you build is both practical and scalable. This approach focuses on solving immediate pain points first and layering in technology as your company's complexity grows.

Crawl: Manual Validation in a Dedicated Channel

The first phase is about building the habit and validating your approval rulebook with zero new software. The immediate goal is to centralize all requests and stop them from getting lost in various channels or direct messages.

Action Steps:

1. Create a Public Channel: Make a new public Slack channel named #finance-approvals or #spend-requests. Making it public provides company-wide visibility into spending, which naturally encourages more responsible requests.
2. Establish a Simple Format: Pin a message to the channel instructing team members on how to submit a request. A simple, consistent format works best.
   • Vendor: Name of the vendor
   • Amount: Total cost (including currency)
   • Purpose: Brief description of the purchase
   • Link: A link to the invoice or purchase page
   • Approver: Tag the designated approver from your rulebook.
3. Approve with Emojis: The tagged approver reviews the request and, if it aligns with the rulebook, reacts with a ✅ emoji. If denied, they can use ❌ and start a thread to explain why. This creates a simple, visual, and searchable approval log directly within Slack.

This “Crawl” stage immediately creates a basic auditable trail and solves the problem of requests getting lost. It costs nothing and can be implemented in under an hour.

Walk: Lightweight Automation with Slack's Workflow Builder

Once your team is comfortable with the dedicated channel, you can introduce simple automation to formalize the process. This phase uses Slack’s built-in tools to make submitting and tracking requests easier and more consistent. As noted in Slack's Workflow Builder, “Slack's Workflow Builder is a native, free feature designed for lightweight automation use cases.”

Action Steps:

1. Open Workflow Builder: In Slack, navigate to your workspace tools and open the Workflow Builder.
2. Create a New Workflow: Start a new workflow and choose the “Shortcut” trigger. Configure the shortcut to be available in your #finance-approvals channel.
3. Build an Input Form: Add a step to “Open a form.” Create fields for Requester, Vendor, Amount, Invoice Link, and Purpose. Make key fields required to ensure you get all the necessary information upfront.
4. Post to the Channel: Add a final step to “Send a message to a channel.” Configure this message to post the submitted form details neatly into the #finance-approvals channel, automatically tagging a specific person (like the finance lead) to triage it. The requester will still need to manually tag the correct approver from the rulebook in a thread.

This “Walk” step structures the data, reduces follow-up questions, and creates a clean, uniform log of all requests. It is a significant move towards a more robust digital approval workflow without any additional software cost.

Run: Integrated Systems for a Scalable Expense Approval Process

The “Run” phase is for when your company’s transaction volume makes manual reconciliation between Slack and your accounting software a major bottleneck. At this point, you need an integrated system that connects approvals, payments, and accounting. This involves adopting dedicated spend management tools. The market has several strong options, and “Dedicated Slack apps for spend management include Clearspend, Ramp, and Airbase.”

When evaluating these platforms, it is important to ensure they provide key features. Good spend management tools should offer features like multi-step approvals and integration with accounting software such as QuickBooks and other platforms. For UK-based companies, look for tools that integrate with Xero to ensure compliance with FRS 102.

A scenario we repeatedly see is: A US-based SaaS company using QuickBooks needs to approve a $2,000/month contract for a new analytics tool. The Head of Product submits the request through an app like Ramp directly in Slack. The system, configured with the approval rulebook, automatically routes the request to the CEO. The CEO receives a Slack notification, reviews the details, and approves it with one click. Once approved, the payment is scheduled, and the transaction is automatically synced to the correct expense category in QuickBooks. This creates a seamless audit trail that satisfies US GAAP requirements and investor scrutiny.

This integrated approach solves advanced pain points by enforcing spend limits, automating the audit trail, and eliminating manual data entry. It also pairs well with formal procurement process design as your buying volume grows.

Practical Takeaways and Next Steps

Implementing a structured approval workflow in Slack is a gradual process that aligns with a startup's growth. The key is to focus on the process before committing to a tool. By defining who can approve what in a simple rulebook, you create the foundation for scalable financial controls. The Crawl-Walk-Run approach ensures you introduce just enough process at each stage without overwhelming your team. Remember to follow government guidance on record keeping for tax where relevant; check official guidance for local requirements in the UK.

To put this into practice, here are your next steps:

• This Week (Crawl): Draft your 2-column approval rulebook in a shared document. Create the public #finance-approvals channel in Slack, pin the request format, and announce the new manual process to your team.
• Next 30 Days (Walk): After the manual process is established, build a simple request form using Slack's Workflow Builder. This step will structure the data and make the process more efficient for everyone.
• Next 90 Days (Run): Assess the time your team spends reconciling approvals from Slack with payments in your accounting platform. If this is becoming a significant time sink, begin evaluating integrated tools like Clearspend, Ramp, or Airbase that connect directly to QuickBooks or Xero.

Continue at the hub: Setting Up Your Finance Function.

Frequently Asked Questions

Q: What is the biggest mistake to avoid when setting up Slack approvals?
A: The most common mistake is focusing on a tool before defining the process. You should first create a clear approval rulebook that outlines who can approve what. A tool should support your process, not dictate it. Starting with a manual "Crawl" phase helps you validate your rules before committing to software.

Q: Why is a public Slack channel recommended for finance approvals?
A: A public channel provides company-wide visibility into spending. This transparency naturally encourages more thoughtful and responsible requests from team members. It also creates a central, searchable log for everyone, preventing approvals from getting lost in private DMs and building a culture of financial accountability.

Q: How should our team handle urgent, out-of-process requests?
A: For truly urgent requests, have a clear exception policy, such as requiring direct founder approval via a specific DM. However, the key is to document the approval in the official #finance-approvals channel after the fact. This ensures the expense is captured in the audit trail and reinforces the importance of the central system.