The Series A Finance Ops Decision Framework: What To Build vs. Buy

# The Series A Finance Ops Decision Framework: What To Build vs. Buy

You just closed Series A. The capital is in the bank. Your team is growing. And suddenly, the financial operations setup that worked for 8 people is crumbling under the weight of 25.

The panic sets in: Do we need to hire a full finance team? Build custom integrations? Buy enterprise software? Hire a fractional CFO?

In our work with Series A startups, we've watched founders make this decision three ways: the overcomplicated way (building custom tools and hiring people they don't need), the underbaked way (ignoring the problem until it breaks quarterly planning), and the right way (using a repeatable framework).

This is the framework.

## Understanding the Three Layers of Series A Financial Operations

Before you decide what to build, buy, or outsource, you need to understand what "financial operations" actually includes at Series A. It's not just accounting. It's not just budgeting. It's an interconnected system of three distinct layers:

### Layer 1: The Data Foundation (Collection & Integration)

This is where your raw financial information lives and flows. It includes:
- Bank account integrations and cash position visibility
- Revenue recognition systems (especially critical for SaaS)
- Expense tracking and receipt management
- Payroll data and benefits administration
- Customer and vendor master data

The key question: How does financial data move from its source (your bank, payment processor, HR system) into a central location where it can be analyzed?

### Layer 2: The Processing Layer (Consolidation & Analysis)

This is where data becomes insight. It includes:
- Monthly close and reconciliation processes
- Account coding and GL mapping
- [CAC attribution and unit economics calculations](/blog/cac-attribution-the-channel-gap-destroying-your-growth-math/)
- Variance analysis and actuals vs. forecast reporting
- Tax provision calculations and compliance prep

### Layer 3: The Output Layer (Reporting & Decision-Making)

This is what leadership actually sees and acts on:
- Management accounting dashboards and KPI tracking
- Board reporting and investor updates
- Cash flow forecasting and runway management
- Departmental P&Ls and cost center accountability
- [Financial metrics that actually inform strategy](/blog/ceo-financial-metrics-the-context-window-problem-nobody-discusses/)

Most founders focus only on Layer 3 when they should be obsessing over Layers 1 and 2. Bad data architecture upstream creates impossible reporting downstream.

## The Build vs. Buy Decision Matrix

Here's what we recommend: **Build almost nothing, buy selectively, and outsource strategically.**

Let me explain why and when to deviate.

### What You Should Always Buy (Don't Build)

**1. Core Accounting & GL Management**

Don't build a general ledger system. Seriously.

Solutions like NetSuite, Sage Intacct, or for lighter-weight operations, QuickBooks Online with proper setups, exist for a reason. They're audited, they're compliant, they integrate with everything else.

We've seen founders waste 6 months building a "lightweight" GL system only to realize they need audit trails, multi-entity consolidation, and tax compliance features they didn't anticipate. By Series A, you should be on a real accounting platform.

**Cost reality:** $200-500/month (QBO) to $1,500+/month (Intacct/NetSuite). This is non-negotiable infrastructure.

**2. Payroll & Benefits Administration**

Payroll mistakes are expensive, legally. Gusto, ADP, or Rippling handle tax compliance, benefits, and reporting that would take your finance person weeks to manage manually.

Buying also means your finance person isn't spending 20% of their time on payroll when they should be analyzing unit economics.

**Cost reality:** $40-60 per employee per month. Worth every penny.

**3. Expense Management & Receipt Capture**

Tools like Expensify, Brex, or Ramp solve both the compliance and the cash flow visibility problem simultaneously. Your employees stop losing receipts, your finance person stops chasing them, and you get real-time spend data.

At Series A growth rates, manual expense management becomes an audit nightmare and a forecasting black hole.

**Cost reality:** $10-30 per employee per month. The compliance risk of not having this exceeds the cost.

### What You Should Build (But Only If...)

**1. Custom Revenue Recognition Logic**

Here's where we often see founders want to build: revenue recognition.

If you have:
- Multi-year contracts with complex recognition schedules
- Variable consideration or usage-based revenue
- Multiple revenue streams with different accounting treatment

...then yes, you may need custom logic. But "custom" usually means working with your accounting software to set up rules and automations, not hiring a developer.

Tools like Stripe Billing, Zuora, or even well-configured NetSuite can handle 95% of use cases without code.

**When to actually build:** Only if you have non-standard revenue models that no existing software handles (rare at Series A). Even then, start with configuration before building.

**2. Departmental Cost Allocation Models**

As you scale, engineering wants to know their true cost. Sales wants to know fully-loaded unit economics including support and infrastructure costs. Product wants to understand the P&L impact of new features.

This requires custom allocation logic: how do you split shared costs (office, infrastructure, finance team itself) across departments?

You *could* do this in Excel, and most Series A startups do. But once you hit 50+ people across 4+ departments, the maintenance burden and error rate become problematic.

Here's what we recommend: Use a simple Python script or Google Sheets + Apps Script that reads from your GL, applies allocation rules, and populates a dashboard. Not fancy. Not overengineered. But maintainable and auditable.

**When to build:** After your first Series A close, if you have 3+ departments and the founding team is tired of manual reallocation.

**Cost reality:** 20-40 hours for a competent engineer or fractional finance person to build and test. Then 2-3 hours per month to maintain.

### What You Should Outsource (Don't Hire Full-Time Yet)

**1. Monthly Close and Reconciliation**

This is the obvious one we see most founders get wrong. They hire a junior accountant or bookkeeper thinking they'll own the monthly close.

What actually happens: The close becomes a bottleneck, quality suffers, and that person becomes a calendar blocker instead of a strategic resource.

Consider outsourcing the actual close work (bank recs, account reconciliations, GL entries, trial balance) to a remote bookkeeping firm like Bench, Mereo, or even your CPA. Keep the analysis and interpretation in-house with your finance lead.

**Cost reality:** $1,500-2,500/month gets you a clean, documented close within 3-5 business days of month-end. This is cheaper and faster than a junior hire.

**2. Tax Compliance and Planning**

By Series A, you have:
- Complex cap table structures
- [Potential R&D tax credit opportunities](/blog/r-d-tax-credits-for-startups-the-payroll-cap-misconception/)
- Multi-entity questions (holding companies, IP companies, etc.)
- Sales tax nexus issues across states
- Equity and incentive stock option implications

This is not something your internal person should own entirely, especially not while scaling.

Partner with a CPA or tax firm that understands startups. Expect to pay $2,500-5,000 per quarter for proactive tax strategy, not just filing.

This isn't an expense—it's an investment. The average Series A startup leaves 15-25k on the table in unclaimed R&D credits alone.

**3. Fractional CFO Services (Strategic Finance)**

Now, here's where we come in—but hear us out.

[Hiring the right financial leadership is one of the hardest decisions a founder makes.](/blog/fractional-cfo-hiring-the-financial-control-gap-founders-actually-face/) A full-time CFO costs $200-250k salary + equity at Series A. But you might not need 40 hours per week of CFO-level work yet.

A fractional CFO (8-16 hours per week) typically costs $4,000-8,000/month and can own:
- Monthly financial planning and analysis
- Board reporting and investor relations
- Headcount and budget planning
- [Cash flow forecasting](/blog/burn-rate-and-runway-the-timing-mismatch-killing-your-fundraising-timeline/)
- Finance team leadership and process design

The key: Fractional CFO *plus* an operations/accounting manager (full-time, $65-85k) is often better than trying to hire a full-time CFO too early.

**Cost reality:** Fractional ($5,000/month) + Operations Manager ($75k/year = $6,250/month) = $11,250/month. A mediocre full-time CFO is $16,000+/month in salary alone.

## The Series A Financial Ops Build vs. Buy Playbook

Let's make this concrete. Here's what we typically recommend to Series A startups:

### Months 1-3 Post-Series A (Foundation)

**Buy:**
- Upgrade to NetSuite or Intacct (if not already)
- Implement Brex or Ramp for real-time expense tracking
- Ensure Stripe or payment processor integrates with GL

**Outsource:**
- Engage a bookkeeping firm for monthly close
- Hire a tax advisor (CPA or startup tax firm)

**Hire:**
- Finance Operations Manager (full-time) or fractional CFO (8-12 hrs/week)

**Don't Touch Yet:**
- Custom dashboards (wait until you know what questions you're asking)
- Departmental P&Ls (structure first, allocations second)
- Forecasting models (data quality must be clean first)

### Months 4-9 Post-Series A (Optimization)

**Buy:**
- Revenue recognition software if your models are complex (Zuora, Stripe Billing)
- Treasury management if you have >$2M cash (Brex Treasury, Mercury Treasury)

**Build (Lightly):**
- Department cost allocation model (as described above)
- Custom KPI dashboard pulling from GL + CRM data

**Outsource:**
- Maintain bookkeeping firm for close
- Expand tax relationship to include quarterly planning

**Hire:**
- If revenue or headcount doubled: Finance Manager (full-time) in addition to Operations Manager

### Months 10-18 Post-Series A (Scaling)

**Build:**
- Revenue reporting integrations (connecting CRM, product data, GL)
- Unit economics dashboards customized to your business model
- Automated variance analysis and forecast-to-actual reporting

**Hire:**
- Full-time CFO if shooting for Series B (can replace fractional)
- Controller or Senior Accountant if multi-entity or scaling internationally

**Outsource:**
- Consider insourcing some close work if you've hit 50+ headcount
- But keep tax strategy outsourced (too complex, too strategic)

## The Infrastructure Debt Trap

Here's what we see go wrong: Founders wait too long, then try to build everything at once.

One client we worked with tried to build a custom revenue recognition system at month 6 post-Series A while their GL was still a mess. Three months later, they had beautiful code that nobody could trust because the underlying data was garbage.

The lesson: **Clean data architecture beats beautiful software every time.**

If you have to choose between buying a $500/month tool that integrates cleanly and hiring an engineer to build something custom, buy the tool. Your bottleneck isn't software—it's data quality and process discipline.

## The Real Cost of Getting This Wrong

Let's talk about what happens when founders make poor build vs. buy decisions:

**Over-building (Common):**
- $40-60k spent on custom tools that could be solved with $300/month SaaS
- Finance person spending 70% of time maintaining systems instead of analyzing
- Audit surprises because custom systems weren't built for compliance
- Scaling becomes a nightmare (nobody knows how the custom tool works)

**Under-investing (Also Common):**
- Monthly close takes 10 days instead of 3 days, killing board prep timing
- Unit economics are a guess because you can't trust the data
- [Tax liability surprises cost $20-50k in penalties and amendments](/blog/r-d-tax-credits-for-startups-the-qualified-research-definition-gap/)
- Series B due diligence reveals financial process chaos, creating investor friction

The middle path—buy the infrastructure, outsource the labor-intensive work, build only what's strategically specific to your business—saves $20-40k per year while reducing risk.

## Your Series A Financial Ops Decision Framework

When you're evaluating any financial operations decision, ask:

1. **Is this a core differentiator for our business?** (If no, buy or outsource)
2. **Does this require significant ongoing maintenance?** (If yes, outsource)
3. **Is this auditable and compliant?** (If no, buy from a vendor, don't build)
4. **Can we get 80% of the value from an existing solution?** (If yes, buy it)
5. **Do we have the operational bandwidth to maintain this?** (If no, don't build)

Apply this framework to every tool, hire, and build decision in your finance operations stack.

## What's Next: Get Your Finance Ops Audit

If you're unsure whether your current setup aligns with this framework, we've created a financial operations audit specifically for Series A startups. It evaluates your current infrastructure against build vs. buy decisions, identifies gaps, and provides a prioritized roadmap.

[Schedule a free 30-minute finance ops audit with our team](/contact/). We'll review your tech stack, process flows, and help you understand what's working and what's silently bleeding efficiency (and cash).

Series A is the inflection point where good financial operations either compound your growth or become your constraint. Get this right, and your finance person becomes a strategic partner. Get it wrong, and they become a bottleneck.