Law Firm Billing and Collections: Billing Cycles, Payment Terms, Fee Disputes, and AR Management

The legal industry has a revenue leakage problem that is unique in professional services. A law firm records billable time, then writes down a portion before invoicing (the “realization rate” on work-in-progress is typically 85-90%), then collects only a portion of what it invoices (the “collection rate” on billed work is typically 85-95%). The combined effect means that a firm with $1 million in recorded time collects somewhere between $720,000 and $855,000. The gap is not a cost-of-doing-business inevitability. It is a management failure that is fixable through billing discipline, payment terms, retainer policies, and collection processes. The tax implications of write-offs, bad debts, retainer accounting, and fee dispute settlements flow directly into the firm’s return and the partners’ K-1s.

How should billing cycles be structured?

Monthly billing is the standard for hourly-fee work, and there is almost no good reason to deviate from it. The longer time sits unbilled, the harder it is to collect. A client who sees a bill for work done 30 days ago can recall the context and assess the value. A client who receives a bill for work done 90 or 120 days ago has lost the connection between the work and the cost, and will scrutinize line items more aggressively.

The billing cycle for each matter should be set at engagement: the engagement letter specifies monthly billing (invoices issued by the 10th of the following month, for example), the payment terms (due upon receipt, or net 15/30), and the consequences of non-payment (the firm may withdraw, interest may accrue, work may be suspended).

Pre-bills. Many firms generate “pre-bills” (draft invoices) that partners review and edit before the final invoice goes to the client. The partner reviews the time entries, writes down excessive or non-value entries, consolidates or rewords descriptions, and approves the invoice. The pre-bill review is where the first round of write-downs occurs. A partner who consistently writes down 20-30% of recorded time has one of three problems: the billing rate is too high for the work, the associates or paralegals are inefficient, or the scope of the engagement was not defined clearly enough to support the recorded time.

Flat-fee billing. For flat-fee matters (estate plans, entity formations, standard filings), the billing is tied to milestones or completion, not to time. The firm should still track time internally (to measure profitability by matter type and to set future flat fees accurately), but the invoice reflects the agreed fee, not the hours. Flat-fee billing eliminates the collection problem for the billed amount (the fee is fixed and agreed in advance), but creates a scope management problem: if the matter requires more work than anticipated, the firm absorbs the cost.

Contingency-fee billing. Revenue is recognized when the case resolves (settlement or verdict). The firm invoices the contingency percentage of the recovery, plus reimbursement of advanced costs. There is no billing cycle during the case. The tax treatment is straightforward for cash-method firms: revenue is recognized when the settlement or verdict proceeds are received.

How do retainers work?

A retainer is money paid by the client in advance of work being performed. The retainer is deposited into the firm’s trust account (not the operating account) and is the client’s money until it is earned. As the firm performs work and issues invoices, the firm transfers the earned portion from the trust account to the operating account (with the client’s authorization, which should be provided in the engagement letter).

Evergreen retainer. The most effective retainer structure is the “evergreen” (or “replenishing”) retainer: the client pays an initial retainer (for example, $5,000), and the engagement letter requires the client to replenish the retainer to the original amount within a specified period (10-15 days) after the firm applies the retainer to an invoice. If the client does not replenish, the firm may suspend work or withdraw.

The evergreen retainer solves the collection problem for the duration of the engagement: the firm always has funds on deposit to cover at least one billing cycle. If the client fails to replenish, the firm learns about the collection problem immediately (when the replenishment is missed), not 90 days later when an invoice goes unpaid.

Flat-fee retainer vs. security retainer. A “flat-fee retainer” (sometimes called a “general retainer” or “availability retainer”) is a fee paid for the attorney’s availability, not for specific work. It is earned when paid and is not deposited in the trust account. This is different from a “security retainer” (advance payment for future work), which is deposited in the trust account and earned as work is performed. The distinction matters for trust account compliance: depositing a flat-fee retainer in the trust account is a technical violation in some jurisdictions (it commingles earned funds with client funds), and failing to deposit a security retainer in the trust account is a serious violation in every jurisdiction.

Tax treatment of retainers. For cash-method firms, the retainer is not income when received (it is a deposit, held in trust). It becomes income when earned (when the firm applies it against an invoice and transfers the funds to the operating account). For accrual-method firms, the retainer is similarly not income when received; it becomes income when the earning event occurs (the work is performed and the invoice is issued).

What are the best collection practices?

Aged receivables follow-up. The firm should generate an AR aging report weekly and assign follow-up responsibility. The standard aging buckets (current, 30, 60, 90+) are less useful than a binary distinction: current (under 45 days) and at-risk (over 45 days). Research on legal billing consistently shows that the probability of collecting a legal fee drops below 50% once the invoice is 90 days old.

Collection calls. The attorney responsible for the client relationship should make collection calls, not administrative staff. The conversation is not “you owe us money.” It is “I want to make sure there is not a problem with the work” (which surfaces fee disputes early) and “let’s talk about a payment arrangement if the full amount is difficult right now” (which converts a dead receivable into a payment plan).

Interest on overdue balances. The engagement letter should specify that interest accrues on overdue balances (at the maximum rate allowed by state law, or a reasonable commercial rate). Interest is rarely the reason a client pays, but it creates a legal basis for the additional charge and signals that the firm treats its invoices as binding obligations.

Suspension of work. The engagement letter should authorize the firm to suspend work if invoices are not paid within a specified period. Suspension is the most effective collection tool the firm has: the client who needs the work done will find a way to pay. The ethical rules permit suspension (and withdrawal) for non-payment in most circumstances, but the firm must not suspend work in a way that prejudices the client (missing a filing deadline, for example). Court permission may be required to withdraw from litigation matters.

Write-off policy. Receivables that are uncollectible should be written off promptly, not left on the books to inflate revenue. A write-off moves the amount from Accounts Receivable to Bad Debt Expense (for accrual-basis firms) or simply removes the receivable from the aging report (for cash-basis firms, since the income was never recognized). The managing partner or a committee should approve write-offs above a threshold (for example, $2,500).

How do fee disputes affect the firm?

Fee disputes are common in legal practice, and the handling of the dispute has both ethical and financial implications.

Fee arbitration. Many state bar associations offer fee arbitration programs. Some states (New York, California, others) require attorneys to inform clients of their right to fee arbitration when a fee dispute arises. Fee arbitration is typically binding on the attorney (if the client elects it) and results in a determination of the reasonable fee. The difference between the billed amount and the arbitrated amount is a write-off.

Suing clients for fees. Filing suit against a client for unpaid fees is permitted but risky: the client will almost certainly counterclaim for malpractice. A $20,000 fee collection lawsuit that triggers a $500,000 malpractice counterclaim is a net loss regardless of outcome. The malpractice insurance carrier should be notified whenever a fee suit is contemplated, and most carriers strongly discourage them.

Tax treatment of fee dispute settlements. For cash-method firms, a fee dispute settlement that results in a reduced payment has no special tax treatment: the firm recognizes income equal to the amount actually collected. For accrual-method firms, if the fee was previously recognized as income (because the work was performed and billed), the reduction is a bad debt deduction under IRC 166 or a reduction of revenue, depending on the firm’s accounting policy.

Contingency-fee adjustments. If a contingency fee is reduced by court order (some courts review contingency fees for reasonableness) or by settlement with the client, the firm recognizes income equal to the amount actually received. No deduction is required for the difference between the original contingency percentage and the reduced amount (because the original amount was never recognized as income).

How does the accounting method affect revenue recognition?

Most law firms use the cash method under IRC 448(c) (available to firms with average annual gross receipts under $31 million for 2025). The cash method provides three advantages:

No tax on uncollected receivables. The firm does not pay tax on billings until the cash is collected. A firm with $500,000 in outstanding receivables at year-end pays no tax on that amount until collected.

No bad debt deduction complexity. Since income is not recognized until collected, there is no need to deduct bad debts. A write-off of uncollectible receivables has no tax effect (the income was never reported). This simplifies the return and eliminates the need to prove that the debt is worthless under IRC 166.

WIP has no tax impact. Unbilled work-in-progress is not a taxable asset. The firm does not pay tax on services performed but not yet billed. This is one of the most significant tax benefits of the cash method for professional service firms: the entire WIP balance is excluded from taxable income.

For accrual-method firms, revenue is recognized when earned (when the services are performed and the amount is determinable), regardless of when collected. This creates a potential tax liability on uncollected receivables and requires the firm to track bad debts and deduct them under IRC 166 when they become worthless. The accrual method is required for firms that do not meet the IRC 448(c) gross receipts test, which in practice means only the largest law firms.

What should I do next?

If your firm does not use an evergreen retainer structure, implement it on new matters immediately and transition existing matters at the next billing cycle. If your AR aging shows receivables over 90 days, assign each one to the responsible partner for a collection call this week. If you do not track the realization rate and collection rate by partner and by practice area, start: those two numbers are the most important financial metrics in a law firm.

• Law firm bookkeeping, the chart of accounts, WIP tracking, client cost advances, and monthly close that produces the billing data
• IOLTA trust accounting, the trust account rules for retainer deposits and earned-fee transfers
• Law firm partner compensation, how partner draws, guaranteed payments, and K-1 allocations connect to the revenue the firm actually collects
• Law firm tax deductions, the deductions unique to legal practice (malpractice insurance, bar dues, CLE, legal research)
• Restaurant bookkeeping, the parallel revenue-leakage analysis (food cost and prime cost) for another industry where the gap between gross and net is the whole ballgame

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.