Cash vs. Accrual Accounting for Law Firms: What Each Method Shows You (and What It Hides)
Most law firm owners never chose how their books get kept. A bookkeeper, a prior accountant, or the default setting in whatever software the firm started with picked cash or accrual accounting long before you had a say, and that one early decision now shapes every financial statement you look at today. It decides whether your numbers reflect what your firm earned or only what has landed in the bank so far, and those two answers can be very different.
Key Takeaways
- Cash basis records income when you’re paid and expenses when you pay them. Accrual basis records income when you bill the work and expenses when you incur them, whether or not the cash has moved yet.
- Cash-basis books can hide a problem: unbilled work and unpaid invoices don’t appear anywhere in your financial statements, even though they represent earned revenue sitting outside the bank account.
- Trust and IOLTA funds follow their own compliance rules no matter which method you use for the rest of your books. Your accounting method choice never touches trust accounting.
- For tax purposes, S corporations and ordinary partnerships can use the cash method regardless of size. The gross receipts test under IRC Section 448 applies only to C corporations and partnerships with a C corporation partner, and the 2026 threshold is $32 million (Rev. Proc. 2025-32), up from $29 million just three years earlier.
- A separate rule most owners never hear about exempts qualified personal service corporations, a category that can include law firms organized as professional corporations, from that test entirely, regardless of revenue.
- Switching methods isn’t something you reverse quietly in a single year. It requires IRS Form 3115 and a formal income adjustment that can stretch across several tax years.
How the Two Methods See Your Firm
Cash basis accounting is where most solo and small firms start, and it’s easy to see why. You record income the day a client’s payment clears and an expense the day you pay the bill, so your books match your bank balance almost exactly, and anyone can read a cash-basis income statement without translation.
Accrual accounting works differently. Revenue shows up when you’ve earned it, meaning the work is done and billed, not when the client pays, and expenses post when you incur them, not when the check goes out. A firm on accrual basis recognizes revenue the month it bills a matter, even if that invoice doesn’t get paid for another ninety days.
Neither version of your books is wrong. They answer different questions. Cash basis tells you what you have right now. Accrual tells you what your firm has earned, whether or not the money has arrived yet.
The Blind Spot Cash Basis Creates
The problem sits in exactly that gap. Picture a firm that bills $3 million a year and collects $2.4 million of it. On cash-basis books, that firm’s income statement shows $2.4 million in revenue and nothing more, with no line anywhere flagging the $600,000 still sitting in unpaid invoices. The firm looks smaller, and depending on timing, less profitable, than it is, and the owner has no way to tell whether that $600,000 gap is a normal billing lag or a collections problem getting worse every quarter.
Work in progress carries the same blind spot. Hours your attorneys have already worked on open matters represent earned value, but under cash accounting none of it appears on the books until it’s invoiced and paid. When a large share of that WIP sits in a handful of big matters, your reported numbers can swing month to month for reasons that have nothing to do with how the firm is performing.
Trust Accounting Doesn’t Care Which Method You Pick
One thing stays constant no matter what you choose for your operating books. Client trust funds, held in your IOLTA account, get tracked under their own compliance rules, separate from whatever accounting method governs the rest of your firm. A cash-basis firm still has to reconcile trust balances to the penny, client by client, the same way an accrual-basis firm does. If your trust accounting has gaps, that’s a more urgent conversation than the one about cash versus accrual (our [trust accounting mistakes guide] covers the most common ways firms put their license at risk there).
The $32 Million Test (and the Exception Almost Nobody Mentions)
For most small and mid-sized firms, the method choice for tax purposes is simpler than it sounds. The restriction on using the cash method under IRC Section 448 applies specifically to C corporations and to partnerships with a C corporation as a partner. If your firm is structured as an S corporation or an ordinary partnership or LLC taxed as a partnership, which describes most firms in this size range, that restriction never applies to you at all. You can use the cash method for tax purposes no matter how large your firm grows.
If your firm is a C corporation, or a professional corporation taxed as one, the gross receipts test decides the question instead. Average your firm’s gross receipts over the prior three tax years, and if that average stays under the threshold, your firm can still use the cash method for tax purposes. The IRS adjusts that threshold for inflation every year. It sat at $29 million in 2023, and for 2026 it’s $32 million under Revenue Procedure 2025-32.
A second path applies even above that number. Qualified personal service corporations are exempt from the cash-method restriction entirely, no gross receipts test required, under IRC Section 448(b)(2). To qualify, substantially all of the corporation’s activities have to involve services in a defined list of fields that includes law, and substantially all of its stock has to be held by current or former employees who perform those services, or their estates. A law firm organized as a professional corporation and owned by its practicing attorneys can often meet both tests regardless of size, which means the $32 million figure is sometimes beside the point entirely.
None of this changes what makes sense for running the firm day to day. It only answers what the IRS will let you file.
Choosing a Method for Decisions, Not Just for the IRS
Even when cash basis is available to you for tax purposes, it isn’t always the right lens for running the firm. A firm under $1 million in revenue can usually get by on cash-basis books alone. Somewhere between $1 million and $5 million, most owners start layering in accrual-style tracking, capitalizing larger assets and keeping receivables visible internally, even while filing taxes on a cash basis. Past roughly $5 million, partner compensation decisions, bank lending, and any conversation about bringing in new partners typically call for full accrual reporting, because lenders and incoming partners want to see what the firm has earned, not just what’s landed in the account so far.
This is also where valuation and succession planning intersect with your accounting method. A buyout built on book value or a revenue multiple depends on accurate figures for work in progress and receivables, numbers that cash-basis books simply don’t carry (our guide on [what your practice is worth] walks through how that valuation math works). The same holds for reading your own [financial statements] with any confidence. A balance sheet built on accrual data tells you something a cash-basis one never will.
If You Decide to Switch
Changing your accounting method isn’t something to decide in the middle of a fiscal year, on a hunch. It requires filing Form 3115 with the IRS and calculating a Section 481(a) adjustment, which captures the income effect of moving from one method to the other. Converting from cash to accrual typically creates a positive adjustment, since receivables and WIP get added back to income, and the IRS generally lets you spread that increase over four tax years instead of absorbing it all at once. Converting from accrual back to cash runs the other direction and usually has to be taken in the year of the change.
Timing the switch matters too. Converting at the start of a year when your receivables happen to be relatively low softens the one-time income bump, which is one more reason this decision belongs in a conversation with your CPA well before year-end, not as a last-minute fix once the books already feel wrong.
Frequent Asked Questions (FAQs)
Which accounting method do most small law firms use?
Most firms under a few million dollars in revenue use cash basis for simplicity, often layering in accrual-style tracking for internal reports as they grow, while still filing taxes on a cash basis where their entity type allows it.
Does changing accounting methods trigger an IRS audit?
Filing Form 3115 for a method change is a routine, expected process, not a red flag on its own. What matters is that the Section 481(a) adjustment is calculated correctly and applied consistently going forward.
Can I keep cash-basis books for taxes and accrual reports for management?
Yes, and many growing firms do exactly that. Your tax return can stay on the cash method while your internal reporting tracks receivables and WIP on an accrual basis, as long as the two sets of numbers are reconciled clearly.
Does my accounting method affect trust accounting or IOLTA compliance?
No. Trust funds are governed by their own reconciliation and recordkeeping rules regardless of which method you use for your operating accounts.
How do I know if my firm needs to switch to accrual?
If you’re applying for financing, bringing in a new partner, planning a sale or succession, or can’t tell from your financial statements whether a slow month is a billing problem or a real one, that’s a strong sign accrual reporting would serve you better, even if your tax return stays on the cash method.
How Silver Peaks CPA Can Help
Your accounting method shapes every number your firm uses to make decisions, from partner compensation to a future buyout. Our accounting and bookkeeping and CFO advisory work for law firms is built to make sure those numbers hold up, whichever method your tax return runs on.
Any other questions, feel free to schedule an informed opinion on where your firm stands.
