Billing is the engine of every law firm. Get it right and the practice runs smoothly, cash arrives on time, and fee earners can focus on client work. Get it wrong and you face mounting work-in-progress, disputed invoices, write-offs, and — in serious cases — SRA intervention. Yet despite its importance, billing remains one of the most neglected disciplines in UK legal practice.

This guide covers everything solicitors and practice managers need to know: the regulatory framework, fee structures, invoicing rules, credit control, and the technology that is transforming how firms bill.

The Regulatory Framework for Solicitor Billing

SRA Standards and Regulations

The SRA Standards and Regulations 2019 (which replaced the old Code of Conduct) set the baseline for billing transparency. Under Chapter 8 of the Code of Conduct, you must ensure clients receive the best possible information, both at the outset and throughout the matter, about the likely overall cost. That obligation is not discharged by a single estimate buried in your client care letter — it is an ongoing duty.

The SRA’s transparency rules, which came into force in December 2018, go further for certain practice areas. Firms offering conveyancing, probate, immigration (non-asylum), employment tribunals, motoring offences, or debt recovery must publish pricing information on their websites. Failure to comply can trigger a regulatory referral.

Beyond the SRA, the Consumer Rights Act 2015 applies where the client is a consumer (not a business). Services must be provided with reasonable care and skill, and if no price is agreed in advance, the client need only pay a reasonable amount. In costs disputes this can be a significant lever.

Solicitors Act 1974 — The Billing Rules

The Solicitors Act 1974 (SA 1974) governs the delivery of bills and the client’s right to challenge them. Key provisions:

Section 69: A solicitor cannot sue for fees unless a bill has been delivered. The bill must be signed by the solicitor or a partner.
Section 70: A client can apply to the court for an assessment of the bill within one month of delivery as of right; between one and twelve months with leave of the court; after twelve months only in special circumstances.
Section 71: Third parties (e.g. a paying party in litigation) can also apply for assessment.

Practically, this means every invoice you send is also a document with legal consequences. Getting the format and content right is not optional.

VAT and Disbursements

Most legal services are standard-rated for VAT purposes. Bills must clearly separate professional fees from disbursements and must show VAT at the correct rate on each. True disbursements (court fees, barrister fees, expert fees) may be treated as disbursements for VAT if you are acting as agent for the client. Where you are the principal — for example when you pay for a search and recharge it — VAT should generally be applied.

HMRC’s VAT Notice 700/44 sets out the rules in detail. Getting this wrong can expose the firm to back-dated assessments.

Fee Structures: Choosing the Right Approach

Hourly Rates

The hourly rate model remains the most common billing method in UK legal practice. The Law Society’s survey consistently shows that over 70% of private practice billings are still time-based. The model works well where scope is genuinely uncertain — complex litigation, corporate transactions, or contentious matters where no two cases are alike.

The risks are well-documented: clients hate not knowing what they will pay, fee earners game timesheets, and pressure to bill hours creates an incentive to do work rather than resolve matters quickly.

If you use hourly billing, you must give a realistic estimate at the outset, update it when things change, and never allow time to stack without client visibility. Monthly billing cycles help; quarterly does not.

Fixed Fees

Fixed fees offer certainty to clients and, if scoped correctly, can improve firm profitability. They work best in commoditised work: residential conveyancing, standard wills, uncontested probates, employment tribunal claims, and straightforward debt recovery.

The discipline is in scoping. A fixed fee that doesn’t account for abortive work, multiple buyer surveys, or a contested probate will haemorrhage margin. Build in clear out-of-scope triggers that convert to hourly billing or a supplementary fixed fee.

According to the Law Society’s 2023 Financial Benchmarking Survey, firms using fixed fees in residential conveyancing report 12% higher recovery rates than those on hourly billing in the same work type, driven by better scoping discipline and reduced write-offs.

Conditional Fee Arrangements

Conditional fee arrangements (CFAs) allow the solicitor to recover a success fee of up to 100% of normal fees if the case succeeds, and nothing (or a reduced amount) if it fails. Since the Legal Aid, Sentencing and Punishment of Offenders Act 2012 (LASPO) came into force in April 2013, success fees and ATE insurance premiums are no longer recoverable from the losing party in most civil cases — they come from the client’s damages.

CFAs require careful financial modelling. You need to know your break-even rate (the success rate below which the model is loss-making) and actively manage your portfolio.

Damages-Based Agreements

Damages-based agreements (DBAs) allow the solicitor to receive a percentage of the client’s damages. In employment cases the maximum is 35%; in other civil cases it is 50%. DBAs remain relatively rare in England and Wales because of structural drafting problems in the 2013 regulations, though the Law Commission has recommended reform.

Retainers and Subscription Models

An increasing number of firms — particularly those serving SMEs — are moving to monthly retainer or subscription models. These provide predictable income for the firm and budgeting certainty for the client. They work best where the client has a steady volume of similar work: employment advice, company secretarial, or property portfolio management.

The Billing Cycle: From Matter Opening to Invoice

Client Care and Costs Estimates

Good billing starts at matter inception. Your client care letter should include:

A clear description of the work to be done
The fee earner responsible and their hourly rate (if applicable)
A realistic overall estimate or range, broken into stages
The billing frequency (e.g. monthly, on completion, at milestones)
Your payment terms
Your complaint procedure

Courts and the Legal Ombudsman consistently find against firms where the client care costs information was vague or never updated. A 2022 Legal Ombudsman annual report found that 38% of costs complaints arose from inadequate costs estimates at the outset.

Time Recording

Accurate time recording is the foundation of billing recovery. Industry benchmarks suggest fee earners should record at least 6 hours per working day on billable matters, with a further 1.5–2 hours on non-billable activity. Firms that fall below 5 billable hours per fee earner per day are typically running at a structural loss.

Time must be recorded contemporaneously. Reconstructed time — logged at the end of the week or, worse, at billing — is consistently under-recorded by 15–25% according to practice management research. The six-minute unit is standard; some firms use three-minute units for high-volume work.

Every narrative should describe what was done, not merely its category. “Correspondence” is not a narrative. “Email to client re amended planning conditions and impact on completion date” is.

Disbursement Management

Disbursements must be captured at the time they are incurred and matched to the correct matter. Uncaptured disbursements — search fees, courier costs, tribunal fees — are a direct write-off. Firms should have a policy requiring fee earners to log disbursements within 24 hours of incurring them.

Maintain a matter-level disbursement ledger and reconcile it before every billing run. Disbursements paid from client account must comply with the SRA Accounts Rules — they can only be drawn once earned.

Drafting and Delivering the Bill

A bill under Section 69 SA 1974 must:

Be in writing (signed or electronically authenticated)
Contain sufficient detail for the client to understand what they are being charged for
Separate professional fees from disbursements
Show VAT correctly

A “gross sum” bill is permitted but risky — clients who receive a large round-number invoice are more likely to dispute it. A detailed narrative bill may take longer to prepare but reduces the dispute rate significantly.

Deliver bills promptly. A bill that arrives two months after the work was done invites a challenge and damages the client relationship.

Credit Control and Getting Paid

Payment Terms and Structures

Standard payment terms in legal practice are 28 days from the date of the invoice. Some firms use 14 days for smaller consumer matters. Longer terms — 60 or 90 days — are occasionally negotiated by large institutional clients but should be avoided unless the relationship justifies it.

Consider requiring payments on account at matter inception and at defined milestones. The SRA permits this provided the money is held correctly in client account. A matter with a £10,000 expected cost might require £3,000 on account at the start, with billing against it monthly.

Chasing Unpaid Invoices

Invoice chasing should be systematic, not ad hoc. A simple escalation schedule:

Day 28: Automated reminder
Day 35: Personal email from the billing solicitor
Day 45: Telephone call
Day 60: Formal letter before action
Day 75: Referral to debt recovery (internal or external)

Research by the Credit Management Research Centre shows that invoices unpaid at 90 days have only a 50% chance of recovery. The cost of chasing increases non-linearly with age. Early, consistent contact is far more effective than a flurry of activity once the debt is already aged.

Retaining a Lien

Where a client refuses to pay and you hold files, you may exercise a solicitor’s lien over the papers. The lien does not extend to original documents held on behalf of third parties, but it covers correspondence files, drafts, and notes. You must not retain papers that are urgently needed to protect the client’s interests, and you must release them if directed to do so by the SRA.

Common Billing Mistakes and How to Avoid Them

Overbilling and Underbilling

Overbilling — charging for more time than was reasonably spent — is a regulatory and reputational risk. The SRA receives hundreds of complaints per year about excessive fees. Underbilling is a profitability problem: the Law Society estimates that firms recover on average only 85% of the time they record, with write-offs at billing a significant component.

Billing Backlogs

A billing backlog is where completed or near-completed work sits uninvoiced. Industry benchmarks suggest that WIP exceeding 45 days’ worth of fees is a cashflow risk. Firms with WIP over 90 days old are often carrying irrecoverable value. Monthly billing disciplines and matter-level targets help prevent accumulation.

Failure to Update Estimates

Where the scope of a matter changes materially, the client must be told promptly and a revised estimate provided. Springing a large final invoice on a client who was expecting a much smaller bill is the most common cause of costs disputes. Document every update in writing.

Technology and the Future of Legal Billing

Practice management software has transformed billing workflows. Systems like Clio, LEAP, and Actionstep automate time capture, generate narratives, and push invoices directly to clients. Firms using integrated billing software report 20–30% improvements in billing realisation rates compared to manual processes.

The next frontier is AI-assisted billing: tools that read emails and calls, draft time entries automatically, and prompt fee earners to approve rather than create records from scratch. Early adopters report significant increases in captured time and reductions in write-offs at the point of billing.

Obiter integrates directly into the billing cycle — reading fee earner emails and activity, automatically generating time entries with accurate narratives, and surfacing unbilled disbursements before the billing run. Fee earners approve in seconds rather than reconstructing records at month end, and billing backlogs that used to take a week to clear often close in a day.

Summary

Good billing is a discipline, not an afterthought. It starts with clear client care information, runs through accurate contemporaneous time recording, captures every disbursement, delivers clear invoices promptly, and follows up unpaid amounts systematically. Firms that embed these practices recover more of the value they create, have fewer disputes, and run healthier cashflows.

Law Firm Billing: The Complete Guide for UK Solicitors