A Series A close is a perfect moment to fix your finance stack — there’s capital, there’s momentum, and the cost of bad infrastructure compounds quickly. The wrong accounting platform at $5M in ARR costs an order of magnitude more to migrate than the right one at $500K. This is the stack we deploy for new Series A clients in their first 90 days, and why.
It’s eight systems across seven categories. Each section explains the operational job the tool is doing, the realistic options, and how we choose between them. None of this is affiliate or sponsored — these are the tools we actually use.
1. Accounting platform
The foundation. Every other system either feeds data into the accounting platform or pulls from it. Getting this wrong means migrating later, which is genuinely painful.
QuickBooks Online. The default for most Series A startups in 2026. It handles the chart of accounts, journal entries, AP, AR, bank reconciliations, and produces standard reports. The Advanced tier supports class and location tracking, which you’ll need for departmental reporting. Strong third-party app ecosystem: integrates cleanly with Ramp, Bill.com, Gusto, and most of the other systems below.
Xero. A perfectly fine alternative to QuickBooks, particularly common for companies founded by Australian or UK operators or with international subsidiary entities. Most US-headquartered Series A startups will land on QuickBooks because the local accounting service market is larger.
NetSuite. The right answer for Series C+ companies with multi-entity consolidation, complex revenue recognition, or international operations. For a Series A startup, NetSuite is dramatically more expensive than the alternatives ($30K+ in annual licensing plus implementation costs), takes 3–6 months to deploy, and provides capabilities you won’t use for two years. We deploy it for companies that have specific needs — multi-entity consolidation, complex inventory, or anticipated IPO trajectory — but the default recommendation for a fresh Series A is QuickBooks.
Sage Intacct. A middle option. Stronger than QuickBooks at multi-entity and revenue recognition, less expensive than NetSuite, but with a smaller integration ecosystem. We use this occasionally for companies with mid-size complexity, but it’s rare for a Series A.
Default recommendation: QuickBooks Online Advanced. Migration to NetSuite or Intacct at Series B or C is straightforward when the time comes.
2. Banking
Where your operating capital sits.
Mercury. The default for most venture-backed Series A startups. Built for startups, clean API, integrates with QuickBooks and the major expense management platforms, FDIC sweep insurance through partner banks, and a reasonable lending product for AR financing if you grow into it.
Brex. Also strong, particularly if you’re using Brex for cards (more on that below). Some companies prefer their cash management product.
Traditional banks (SVB, JPMorgan, First Republic alumni). Useful when you need wire transfers in unusual jurisdictions, complex treasury arrangements, or a relationship banker who can introduce you to debt providers. For most Series A startups, you don’t need this yet. You can open a relationship account at a major bank as a secondary in case you need it.
Default recommendation: Mercury as primary, with a secondary at a traditional bank for backup and treasury. Spread cash across two banks once you cross $2M in operating capital.
3. AP and bill pay
Paying vendors. This used to be a Bill.com question. It increasingly isn’t.
Bill.com. The historical incumbent. Still works well, particularly if your accounting partner is already trained on it. Slightly cumbersome UI, but the integrations are deep.
Ramp Bill Pay. Bundled with Ramp’s expense management. If you’re already on Ramp for cards (almost everyone is), adding bill pay is friction-free and free. The UI is dramatically better than Bill.com, and approvals work cleanly.
Brex Bill Pay. Equivalent product to Ramp’s. Pick based on which spend platform you’re using.
Default recommendation: Ramp Bill Pay if you’re on Ramp for cards (which most Series A startups are). Bill.com only if you have a specific reason — usually because your accounting partner is locked into it.
4. Expense management and corporate cards
How everyone in the company spends money.
Ramp. The default. Free, well-integrated with QuickBooks, strong policy controls, generous rewards. Categorizes transactions automatically and pushes them to your accounting platform. Their Vendor Bill Pay product is genuinely good.
Brex. Comparable. Stronger international card product, slightly different rewards structure. Some companies prefer Brex’s treasury and banking integration if they’re consolidating with Brex for cash.
Mercury Cards. A simpler product than Ramp or Brex. Fine if you’re a 10-person company and you want one less vendor. Less useful past 30 employees when expense policy enforcement and accruals become more involved.
Default recommendation: Ramp. Most of our Series A clients land here, with a Brex evaluation if there’s a specific reason.
5. Payroll
How you pay employees, and where most of the multi-state compliance work lives.
Gusto. The default for Series A companies under 50 employees. Easy to use, multi-state support is reliable, integrates with QuickBooks and the major HRIS platforms, handles 1099s and W-2s cleanly. Their benefits brokerage is fine but not strong; many companies use Gusto for payroll only and a separate broker.
Rippling. Stronger if you’re consolidating payroll + HRIS + IT provisioning under one platform. More expensive than Gusto, but the value compounds at 50+ employees with multi-state operations. Many of our Series A clients move from Gusto to Rippling between 30 and 60 employees.
Justworks. A PEO model. The PEO becomes the legal employer of record, simplifying multi-state compliance but giving up some control over benefits and policies. Useful for companies that don’t want to deal with multi-state registration themselves and aren’t planning to grow past 75 employees quickly.
TriNet. Another PEO. Similar tradeoffs to Justworks, generally more expensive but with broader benefits packages.
ADP. Enterprise-grade, but overkill for Series A. Most companies don’t move to ADP until they’ve outgrown Rippling at several hundred employees, if then.
Default recommendation: Gusto for under 30 employees, Rippling for 30+ unless there’s a reason to use a PEO.
6. Equity management
The system of record for your cap table, options, and 409A coordination.
Carta. The default. Excellent cap table management, option granting workflows, vesting tracking, 409A valuations included (or through a partner). The reporting that comes out of Carta integrates cleanly with audit prep and stock comp expense calculations.
Pulley. A real competitor to Carta, generally cheaper, with a strong product and a customer base that includes a number of high-profile Series A startups. We’ve migrated companies in both directions; both work. Pulley is often the better choice if cost matters and you don’t have a specific reason to use Carta.
Shareworks (Morgan Stanley). Enterprise-grade. Useful for companies preparing for IPO. Not the right fit for a Series A.
Default recommendation: Carta or Pulley. Either is fine; choose based on price and any preference from your law firm or investors.
7. Revenue, billing, and invoicing
How customers pay you.
Stripe. The default for SaaS and most software companies. Strong APIs, predictable behavior, reasonable rates. Works for subscription billing if you build it yourself or use Stripe Billing.
Maxio (formerly Chargify + SaaSOptics). Useful for SaaS companies with complex billing — usage-based pricing, custom invoicing schedules, multi-tier subscriptions, deferred revenue accounting. Maxio handles the ASC 606 revenue recognition work that Stripe alone doesn’t, and pushes clean entries into QuickBooks or NetSuite. We add Maxio for clients with non-trivial subscription complexity, often around the Series B raise.
Chargebee. Comparable to Maxio. Either works.
Default recommendation: Stripe alone for simple subscription models. Stripe plus Maxio or Chargebee when revenue recognition gets complex enough that calculating it in QuickBooks by hand is no longer reasonable.
8. Reporting and dashboards
Where the board package and KPI tracking live.
For Series A: Excel or Google Sheets, refreshed monthly from QuickBooks exports. This sounds primitive but it’s correct. A dedicated BI tool at this stage is over-investment — you’ll spend more time configuring it than you’ll save in reporting time, and your metrics aren’t yet stable enough to lock into a BI schema.
For Series B+: Mosaic, Drivetrain, or Tesorio for finance-specific reporting and forecasting. Or a general BI tool like Looker, Metabase, or Hex if you have data engineering capacity. We deploy these on a case-by-case basis when monthly reporting workload exceeds what spreadsheets can absorb gracefully.
Default recommendation for Series A: Spreadsheets, refreshed by the fractional CFO or controller monthly. Add a dedicated FP&A or BI tool only when you have a specific operational pain it solves.
How the stack fits together
A typical Series A stack ends up looking like this:
- Accounting: QuickBooks Online Advanced
- Banking: Mercury + secondary
- AP/Bill Pay: Ramp Bill Pay
- Expenses/Cards: Ramp
- Payroll: Gusto (or Rippling if 30+)
- Equity: Carta or Pulley
- Revenue: Stripe (plus Maxio if SaaS complexity warrants)
- Reporting: Spreadsheets, refreshed monthly
Total monthly software cost: roughly $1,200–$2,500 depending on headcount and tier. The right stack is not the most expensive one — it’s the one that produces clean data without manual reconciliation.
What Pegacorn does
When we take on a Series A accounting engagement, deploying this stack is part of the first 90 days. We migrate companies into it, configure the integrations correctly, and own the operational work of running it once it’s live. If you’re already on most of these systems but they’re not configured cleanly or not integrated properly, we’ll audit the setup and fix the gaps. Either way, the goal is the same: financial data you can trust, produced without manual reconciliation, every month.
If your stack has accumulated over time and isn’t producing reliable monthly financials, we can scope a cleanup engagement.