Building a Busy-Season Capacity Worksheet Before You Buy ERP

Pull three numbers by month for the last two years: billed revenue, staff hours worked, and cash collected. Lay them side by side. Most firms discover their busiest billing month and their busiest staffing month aren't the same month, because work performed during the compression period often doesn't get invoiced until weeks later. That lag is exactly what a general ledger built for steady monthly revenue struggles to represent clearly, and it's the real test to run against any ERP before you sign anything.

If your worksheet shows collections consistently trailing billing by a wide margin, that's a cash planning problem your next system needs to make visible early, not a surprise you discover again next April.

CPA firms need something closer to engagement-based accounting than general project accounting: tracking realization (billed value against standard rates) and write-downs (the gap between standard billing and what a client actually pays) by engagement, partner, and service line, all at once. A tax engagement, an audit engagement, and an advisory engagement behave differently in terms of both timing and margin, and lumping them into one project category hides exactly the information a managing partner needs at review time.

Gross margin by service line also tends to look meaningfully different between audit, tax, and advisory work inside the same firm, and comparing yours against a single industry-wide figure can mislead you about which line is actually carrying the practice¹.

For a single-office or two-office firm, Sage Intacct's project and dimensional accounting tends to map more directly onto how a CPA practice actually operates: tagging revenue and cost by engagement, partner, and service line without a heavy custom build. Its faster implementation timeline also matters for a firm that can't afford a long system transition to collide with a busy season.

Receivables discipline deserves its own look here too, since a firm that lets client receivables days run long is effectively extending free financing to clients who could pay faster².

Once a firm has grown into several offices, possibly under different legal entities after a merger or acquisition, NetSuite's multi-subsidiary consolidation becomes the more direct path to a single firm-wide view instead of stitching together separate instances or manual roll-ups. That's a real, specific trigger, not a general size threshold: a firm can have plenty of staff and still run cleanly on Sage Intacct if it's operating as one legal entity out of one location.

A merger brings its own migration headache regardless of platform: two firms almost never share a chart of accounts, a fee schedule, or a partner compensation formula, and reconciling those differences before go-live matters more to a clean transition than which ERP name is on the contract.

There's a credibility angle here too. A firm that advises clients on choosing accounting systems and financial controls should be able to point to its own books as a working example, not an exception. If your own realization and WIP tracking are held together with a spreadsheet a partner built years ago, that's worth fixing before the next client asks how you'd solve the same problem for them. Staffing costs matter directly here as well: the national median wage for accountants and auditors is $83,680 a year, a real input if you're budgeting for additional staff capacity to handle a growing engagement list³.

Ask each vendor to configure one full busy-season scenario using your own numbers: a batch of tax returns billed in a compressed window, a handful of write-downs on fixed-fee engagements, and a partner draw against a retainer paid up front. Watch how many manual adjustments it takes to get realization and WIP reporting correct for that batch. If the answer is more than a couple of workarounds, that's a signal worth weighing seriously, since it's the exact scenario you'll be running every year during your busiest weeks, not an edge case.

Also ask how the system handles partner-level profitability once compensation is tied to origination and delivery credit separately, since that calculation needs clean data flowing from engagement tagging rather than a side spreadsheet reconstructed each quarter.

Ask each vendor to configure one busy-season scenario using your own numbers:

• A batch of tax returns billed in a compressed window, to see how revenue and cash collections line up against staff hours.
• A handful of write-downs on fixed-fee engagements, tracked as realization by engagement, partner, and service line.
• A partner draw against a retainer paid up front, and how it flows through the books.
• The number of manual entries needed to book the scenario correctly, since that count shows how much the system does for you.