Law firm cost structure: where the money actually goes

A law firm's costs are mostly people. The Law Society's 2026 Financial Benchmarking Survey reported a median cost of £70,551 per fee-earner, plus £27,061 of support staff and £46,916 of other overheads per fee-earner. Non-salary overheads were 28.4% of fee income. Premises, professional indemnity insurance, technology and marketing make up most of the rest.

The useful question is not what the costs are but what one chargeable hour costs to deliver, because that sets the floor for every price the firm quotes. This post is part of our series on law firm profit margins and what drives them. It is an operations view. How costs are treated in your accounts, and for tax, is for your accountant.

What are the main costs of running a law firm?

Grouped the way most management accounts present them:

• Fee-earner salaries and employment costs. The largest single line. Salary, employer's National Insurance, pension, and any bonus.
• Support staff. Secretaries, receptionists, accounts, IT, practice management. Often underestimated because they are spread across teams.
• Premises. Rent, business rates, service charges, utilities.
• Professional indemnity insurance. Compulsory for SRA-regulated firms and a significant cost for small firms.
• Technology. Practice management, case management, accounts software, telephony, cyber security.
• Regulatory and professional fees. Practising certificates, SRA fees, memberships.
• Marketing and business development.
• Finance costs. Overdraft and loan interest, and bank charges.

Partner drawings are usually not a cost in the accounts of a partnership or LLP; they are a share of profit. That distinction changes every ratio below, which is why it is worth being clear about.

What do the UK benchmarks say about law firm costs?

Two published sources, measuring slightly different things:

• The Law Society Financial Benchmarking Survey 2026 (121 firms, produced by Hazlewoods, published April 2026) reported a median fee-earner cost of £70,551, down 0.4%; support staff spend of £27,061 per fee-earner; non-salary overheads of £46,916 per fee-earner; and non-salary overheads at 28.4% of fee income, down from 31%. The Law Gazette's coverage added that IT costs were over 4% of fee income and professional indemnity insurance fell as a share of fee income for the first time in seven years.
• Armstrong Watson's Law Firm Benchmarking Review 2024/2025 (published February 2026) reported staff costs at 38.9% of fee income, rent and rates at 4.1%, PI insurance at 4.8% (5.1% for firms with one to seven partners) and marketing at 4.4% (5% for small firms).

The Law Society's 2025 survey reported total salary costs at 63.5% of fee income. That is very different from Armstrong Watson's 38.9%. The published summaries do not set the definitions side by side, and the likeliest difference is whether partners' notional salaries are counted. Before you compare your own firm with either, find out what each ratio includes.

How do you work out the cost of a fee-earner hour?

This is the most useful calculation in the whole post, and many firms never do it. The Law Society's 2025 survey summary reported a median hourly cost per fee-earner of £123.40, against median hourly fees of £133.01. That thin gap is the whole business.

The method, step by step:

• Step 1. Total the fee-earner's direct cost: salary, employer's National Insurance, pension and benefits.
• Step 2. Allocate a share of support staff and overheads. Divide the firm's total support and overhead costs by the number of fee-earners, or weight by fee income if roles differ a lot.
• Step 3. Add the two. That is the fully loaded annual cost.
• Step 4. Divide by realistic chargeable hours, not target hours.

A worked example, with invented numbers:

• A hypothetical associate costs £58,000 in salary plus £9,000 of employer costs: £67,000.
• The firm allocates £60,000 of support and overhead per fee-earner.
• Fully loaded cost: £127,000 a year.
• At 1,100 target hours, the cost per hour looks like £115.
• At 800 actual chargeable hours, it is £159.

That difference changes pricing. If this associate's rate is £180 and realisation is 85%, the firm earns about £153 per recorded hour, which is below the £159 it costs. The associate is busy, the rate looks healthy, and every hour loses money. The real problem is not the rate; it is the hours. See billable hours in UK law firms.

Which law firm costs are fixed and which are variable?

Most of a law firm's cost base is fixed in the short term. Salaries, rent and insurance do not fall when a month is quiet. That has two consequences.

• Revenue shortfalls go straight to profit. A 10% fall in fees can remove a much larger share of profit, because costs do not move with it.
• Extra revenue from existing capacity is very profitable. An instruction handled by a fee-earner who had spare hours costs the firm little beyond disbursements. That is why winning enquiries you already receive is worth so much more than it looks.

A quick illustration, with invented numbers. A hypothetical firm bills £1,000,000 against £800,000 of largely fixed costs, leaving £200,000. If fees fall 10% to £900,000 and costs barely move, profit falls to about £100,000: half of it gone from a tenth of the fees. The same arithmetic works in reverse. Ten per cent more fees from the same team roughly adds half as much again to profit. That asymmetry is the single most important fact about a law firm's cost structure, and it is why the front door matters as much as the cost lines.

Genuinely variable costs are few: disbursements (usually passed on), some marketing, agency or locum fees, and bonuses.

How does firm size change the cost structure?

Some costs scale with the firm and some do not. The published figures show the pattern. Armstrong Watson's 2024/25 review reported professional indemnity insurance at 5.1% of fee income for firms with one to seven partners, against 3.4% for firms with eight or more partners. Small firms also spent more of their fee income on marketing: 5%, against 4.4% across all firms.

The operational reasons are familiar. A small firm pays for a practice management system, a phone system, an accounts package, cyber insurance and a compliance function whether it has three fee-earners or thirty. Those costs are lumpy: they arrive in steps, not in proportion to fees. That is one reason small firms feel cost pressure first, and one reason growth from existing capacity is so valuable to them.

How should a small firm budget its costs?

A simple approach I would use for a firm of under twenty people:

• Start from people. List every role with its fully loaded cost. This will be most of the budget.
• Add the fixed platform. Premises, insurance, regulatory fees, systems. These do not move month to month.
• Set a marketing budget as a share of target fee income, and decide in advance what each channel must produce in enquiries.
• Hold a contingency for recruitment, PI renewal surprises and system changes.
• Compare the total with realistic fee income, built from actual chargeable hours and realisation, not targets.

If the budget only balances at target hours, it does not balance.

How can a law firm reduce its costs without harming service?

Cost cutting in professional services has a poor record when it removes the people who serve clients. Before cutting, check whether the cost is actually buying anything. A short review list:

• Premises. How many desks are used on an average day? Hybrid working has changed the answer for many firms.
• Software. List every subscription and who uses it. Duplicate tools are common after years of piecemeal buying.
• PI insurance. Claims history, risk management and the quality of the proposal form all affect premiums. A broker who specialises in law firms can advise.
• Support ratios. Not whether you have too many support staff, but whether fee-earners are doing support work at fee-earner cost.
• Unbilled fee-earner time. Admin, chasing and status calls done by fee-earners are a cost that never appears on a line.

What is the hidden cost in a law firm's cost structure?

Two costs never appear in the management accounts.

The first is fee-earner time that produces no fee. The gap between the hours a fee-earner is paid for and the hours that become chargeable is spent somewhere: supervision, admin, business development, and a great deal of phone and email traffic. Some of that is valuable. Some of it, like repeated "where are we?" calls from clients who have not had an update, is avoidable.

The second is the instruction the firm never won. A caller who reaches voicemail and rings the next firm costs nothing on paper. Yet the firm has already paid for the marketing, the website, the premises and the fee-earner capacity that would have handled that matter. Because fixed costs are already sunk, a lost instruction takes almost its whole fee out of profit. We walk through how to size it in what missed enquiries cost a law firm.

A checklist for your own cost review

• Calculate a fully loaded cost per chargeable hour for each fee-earner grade.
• Compare it with the realised (not rate card) income per hour.
• Separate client account interest from trading income.
• Allocate overheads to departments on a stated basis and look for cross-subsidy.
• List the tasks fee-earners do that someone else could do at lower cost.
• Estimate how many enquiries the firm does not answer each month.

Where does WasilX fit?

We work on those two hidden costs. Cam, our AI Engagement Coordinator, takes calls on the firm's line at any hour, says it is AI, asks the firm's qualifying questions, books the call back and sends a summary, so enquiries stop leaking to voicemail. Each fee-earner's personal assistant covers their calls while they are in court and drafts matter updates for the fee-earner to approve, which takes some of the unbilled update traffic off their day. To see what that is worth against your own cost base, start a conversation with us.

For how cost translates into price, see law firm pricing strategies and how to price fixed fees.

Frequently asked questions

What is the biggest cost for a law firm? People. Fee-earner and support staff costs together are the largest part of almost every firm's cost base, followed by premises, professional indemnity insurance and technology.

What percentage of fee income should overheads be? The Law Society's 2026 Financial Benchmarking Survey reported median non-salary overheads of 28.4% of fee income. Use it as context rather than a target, and check the definition before comparing.

How much does a fee-earner cost a law firm? The Law Society's 2026 survey reported a median fee-earner cost of £70,551, before support staff and overheads. The fully loaded cost, including a share of those, is much higher.

How do you calculate the cost per hour of a solicitor? Add salary, employer costs and a share of support and overheads, then divide by the chargeable hours the solicitor actually records, not the target.

Are partner drawings a cost? In a partnership or LLP they are usually a share of profit, not a cost. That is why margins look higher in partnerships. Your accountant can confirm the treatment in your accounts.