Detailed Assessment of Costs: A Practical Guide

Practice Guides — 2026-03-24

Step-by-step guide to detailed assessment under CPR Part 47: notice of commencement, points of dispute, replies, provisional assessment and the final hearing.

Detailed assessment is the formal court process for determining the amount of legal costs payable by one party to another. It is the mechanism by which a costs order is converted from a general entitlement ("the defendant shall pay the claimant's costs") into a specific sum.

Whether you are a solicitor preparing to recover your client's costs or a litigation lawyer defending a bill you consider excessive, understanding the detailed assessment procedure is essential. This guide sets out the process from start to finish, with practical tips drawn from our experience handling assessments at every level.

When Does Detailed Assessment Apply?

Detailed assessment applies whenever costs are to be assessed by the court rather than agreed between the parties. This typically arises in three situations:

Inter partes costs following a court order (for example, after trial or summary judgment)

Solicitor and client assessments under the Solicitors Act 1974

Legal aid assessments of publicly funded costs

In most inter partes cases, the parties will first attempt to negotiate. Detailed assessment is the fallback when agreement cannot be reached. It is governed by CPR Part 47 and its associated Practice Direction.

It is worth noting that the court actively encourages negotiation. The costs of the detailed assessment itself can be significant, and a party who refuses a reasonable offer to settle may find themselves penalised in costs, even if they achieve a better result on assessment.

Commencing Proceedings: The Notice of Commencement

The receiving party (the party entitled to costs) begins the detailed assessment process by filing a request for a detailed assessment hearing, together with:

Form N252 (the Notice of Commencement)

A copy of the bill of costs

Copies of the costs order(s) and any relevant orders

The fee notes of counsel and any expert

Any written evidence as to disbursements exceeding £500 (receipts, invoices)

A statement of the costs the receiving party is seeking

Time Limit for Commencing

Under CPR 47.7, the receiving party must commence detailed assessment proceedings within three months of the date of the costs order (or the date of the event giving rise to the right to assessment). Missing this deadline does not extinguish the right to costs, but the court may disallow interest on costs for the period of delay, and the paying party can apply for an "unless" order requiring commencement within a specified period.

Practical tip: Do not let the three-month deadline drift. Even where negotiations are ongoing, it is good practice to serve the Notice of Commencement within time and then continue negotiations in parallel. You protect your position without prejudicing settlement discussions.

The Bill of Costs

The bill must comply with Practice Direction 47. Following the costs reform of 2022, bills for work done after 6 April 2022 must be in the new electronic "J-Codes" format. For work done before that date, the traditional format applies. Many bills cover both periods and therefore have two parts.

The bill should be detailed enough to allow the paying party to understand what work was done, by whom, at what rate, and why. A poorly drafted bill invites excessive points of dispute and makes the assessment harder for everyone.

Points of Dispute

The paying party's response to the bill takes the form of Points of Dispute. These are the paying party's formal objections to the costs claimed.

Time Limit

Under CPR 47.9, Points of Dispute must be served within 21 days of service of the Notice of Commencement. This is a hard deadline: if the paying party fails to serve Points of Dispute in time, the receiving party may apply for a default costs certificate (see below).

Extensions of time can be agreed between the parties (up to a maximum of 28 days by consent without court permission) or sought from the court. In practice, reasonable requests for short extensions are usually agreed.

What Must They Contain?

Practice Direction 47, paragraph 8.2 sets out the requirements. Points of Dispute must:

Identify each item in the bill which is disputed

State concisely the nature and grounds of the dispute

Where practicable, suggest a figure to be allowed for each disputed item

This last point is important and often overlooked. Generic objections such as "excessive" or "unreasonable" without proposing an alternative figure are unhelpful and may attract criticism from the court. The best Points of Dispute are specific: they identify precisely what is challenged and why, and they put forward a realistic counter-proposal.

Practical tip for paying parties: Points of Dispute are your opportunity to set the agenda for the assessment. Take them seriously. Well-drafted points that engage properly with the bill will carry more weight with the costs judge than sweeping, generic challenges.

Practical tip for receiving parties: Read the Points of Dispute carefully. They often reveal the paying party's strategy and priorities. Items that attract only token challenges may indicate where the paying party expects to concede.

Replies to Points of Dispute

The receiving party may serve Replies to Points of Dispute, though this is optional. If Replies are to be served, they must be filed within 21 days of service of the Points of Dispute (CPR 47.13).

Replies should address the specific objections raised and provide any further evidence or argument in support of the costs claimed. They are particularly useful where the Points of Dispute raise factual challenges that can be answered with evidence, or where the receiving party wants to correct misunderstandings about the work done.

Practical tip: Replies are not always necessary. If the Points of Dispute are weak or generic, silence can be more effective than a detailed response. However, if the paying party has raised substantive points that might mislead the court, a Reply is advisable.

Default Costs Certificates

If the paying party fails to serve Points of Dispute within the 21-day time limit (or any agreed extension), the receiving party can apply for a default costs certificate under CPR 47.11. This is a certificate for the full amount of the bill, plus fixed costs of the assessment proceedings and court fees.

A default costs certificate is a powerful tool. Once issued, it has the same effect as a final costs certificate and is enforceable as a judgment.

Setting Aside a Default Costs Certificate

The paying party can apply to set aside a default costs certificate under CPR 47.12. The court will set it aside if it is satisfied that there is good reason to do so. Relevant factors include:

Whether the failure to serve Points of Dispute was due to a good reason (illness, administrative error, etc.)

Whether the application to set aside was made promptly

Whether the paying party has a real prospect of successfully challenging a significant proportion of the bill

The court has a broad discretion, but a paying party who simply ignored the deadline without good reason will face an uphill struggle.

Practical tip for receiving parties: Always apply for a default costs certificate promptly when Points of Dispute are late. Even if it is subsequently set aside, it puts you in a strong negotiating position and signals that you are running a tight ship.

Provisional Assessment

For bills of costs that do not exceed £75,000, the court will undertake a provisional assessment under CPR 47.15. This applies to most between-the-parties assessments and is the default process at the SCCO (Senior Courts Costs Office) and in most regional costs centres.

How Provisional Assessment Works

Provisional assessment is a paper-based process. There is no hearing. The costs judge considers the bill, Points of Dispute, any Replies, and written submissions from both parties, then makes a provisional assessment of each disputed item.

Both parties may file written submissions in support of their respective positions. These are important: they are your opportunity to guide the costs judge through the key issues and draw attention to the strongest points.

The court will then issue its provisional assessment, setting out the figure allowed for each disputed item.

The Deemed Costs Cap

A significant feature of provisional assessment is the cap on the costs of the assessment itself. Under CPR 47.15(5), the court will not award more than £1,500 (plus VAT and court fees) as the costs of the provisional assessment proceedings, unless there are exceptional circumstances. This cap applies to both sides.

The effect of this cap is to encourage proportionate conduct. There is limited financial incentive to instruct expensive counsel to draft elaborate written submissions for a provisional assessment, because the costs recovery is capped regardless.

Challenging the Provisional Assessment

If either party is dissatisfied with the provisional assessment, they may request an oral hearing within 21 days of receipt of the court's decision. However, there is a costs risk: if the party requesting the hearing fails to achieve a result that is at least 20% more favourable than the provisional assessment, they will bear the costs of the oral hearing.

Practical tip: Think carefully before requesting an oral hearing. The 20% threshold is significant. Unless the provisional assessment contains clear errors or you are confident of achieving a substantially better result, the costs risk may outweigh the potential benefit.

Oral Assessment Hearing

Where the bill exceeds £75,000, or where a party has requested an oral hearing following provisional assessment, the matter will be listed for an oral hearing.

What Happens at the Hearing

At the SCCO, detailed assessment hearings are conducted before a costs judge or, in some cases, a costs officer. The hearing is relatively informal compared to a trial, but it follows a structured process:

1. The costs judge will work through the bill item by item (or, more commonly, will focus on the items in dispute)

2. Both parties have the opportunity to make submissions on each disputed item

3. The receiving party bears the burden of establishing that the costs claimed are reasonable and proportionate

4. The costs judge makes a ruling on each item, either allowing it, reducing it, or disallowing it entirely

Hearings can last anywhere from half a day to several days, depending on the size and complexity of the bill. For substantial bills, it is common for the parties to agree many items in advance, leaving only the genuinely contested points for the judge.

Preparation for the Hearing

Preparation is critical. Before the hearing, you should:

Attempt to narrow the issues by negotiation

Prepare a schedule showing agreed and disputed items

Have authorities ready for any legal arguments (e.g., on hourly rates, proportionality)

Be ready to explain the background to the litigation and why particular items of work were necessary

Practical tip: Costs judges appreciate efficiency. Coming to the hearing with a clear schedule of issues, having agreed as much as possible, will create a favourable impression. Conversely, arriving with hundreds of disputed items, many of which are trivial, will not.

Interim Costs Certificates and Payments on Account

During the detailed assessment process, which can take many months, the receiving party may need access to funds. Two mechanisms can assist.

Payments on Account

Under CPR 44.2(8), the court will order a payment on account of costs unless there is good reason not to. This is typically ordered at the same time as the costs order itself, before detailed assessment has even commenced. The court will assess a reasonable proportion of the likely eventual costs, usually in the range of 60% to 80% of the budgeted or estimated costs.

Interim Costs Certificates

During the detailed assessment process itself, the receiving party can request an interim costs certificate under CPR 47.16. This allows the receiving party to obtain a certificate for costs already agreed or which are clearly due, without waiting for the entire assessment to conclude.

Practical tip: If a significant proportion of the bill is uncontested or has been conceded in Points of Dispute, apply for an interim costs certificate. There is no reason why the receiving party should be kept out of money that is clearly due.

Offers to Settle Costs Proceedings

Settlement offers play a crucial tactical role in detailed assessment. There are two main vehicles.

Part 36 Offers

Part 36 of the CPR applies to detailed assessment proceedings. A receiving party can make a Part 36 offer stating the sum they would accept in settlement of the bill. A paying party can make a Part 36 offer stating the sum they are prepared to pay. The usual Part 36 costs consequences apply: if the receiving party obtains a result at least as advantageous as their own Part 36 offer, the paying party will typically be ordered to pay indemnity costs and enhanced interest from the expiry of the relevant period.

Calderbank Offers

Calderbank offers (named after the case of Calderbank v Calderbank [1975]) are "without prejudice save as to costs" offers. They do not carry the automatic consequences of Part 36 but are taken into account by the court when deciding the costs of the assessment.

Practical tip: Always make an early offer. If you are the receiving party, a well-judged discount of 10% to 15% from your bill, made early in proceedings, puts significant costs pressure on the paying party. If you are the paying party, a realistic offer based on proper analysis of the bill protects your position on the costs of the assessment.

Costs of the Assessment

The general rule is that the receiving party is entitled to the costs of the detailed assessment proceedings (CPR 47.20). However, this is subject to the court's discretion, and the court will have regard to:

The conduct of the parties

The amount by which the bill has been reduced

Whether it was reasonable to contest particular items

Where the bill is reduced by a significant margin, the court may reduce or disallow the receiving party's costs of the assessment, or even order the receiving party to pay the paying party's costs. This is particularly likely where the bill as served was significantly inflated or included items that should never have been claimed.

The practical implication is clear: serve a realistic bill. A bill that is padded in the hope of negotiating down invites a punitive costs order on the assessment itself.

Common Tactical Considerations

For Receiving Parties

Serve a well-drafted, realistic bill. The bill sets the tone. An inflated bill invites aggressive Points of Dispute and undermines your credibility.

Commence within the three-month deadline. Protect your position even if negotiations are ongoing.

Make a Part 36 offer early. A modest discount, offered early, puts pressure on the paying party and protects your costs position.

Consider an interim costs certificate if substantial sums are uncontested.

Prepare thoroughly for any hearing. Narrow the issues in advance and come with a clear schedule.

For Paying Parties

Serve Points of Dispute on time. A default costs certificate is embarrassing and expensive to set aside.

Be specific in your challenges. Propose realistic alternative figures. Generic objections carry little weight.

Make a realistic Calderbank or Part 36 offer based on proper analysis, not just a lowball figure.

Pick your battles. Focus on the high-value items where the reductions will be meaningful. Challenging every six-minute unit of attendance wastes time and costs.

Consider the 20% threshold before requesting an oral hearing after provisional assessment.

Practical Timeline Summary

Below is a typical timeline for a detailed assessment from start to finish:

In practice, the entire process from costs order to final resolution can take anywhere from six months to over a year, depending on the complexity of the bill and the court's listing availability. Negotiation at any stage can shorten this significantly.

Key Takeaways

Detailed assessment is a structured process, but it rewards preparation, realism, and tactical awareness. Whether you are claiming costs or defending them, the most important factors are:

1. Serve a proper bill or proper Points of Dispute. Quality of drafting matters.

2. Make early, realistic offers. The costs of the assessment itself can erode the value of any recovery.

3. Know the deadlines. Missing a time limit can have serious consequences.

4. Prepare for hearings. Narrow the issues, agree what you can, and focus on the points that matter.

5. Instruct a specialist. Costs law is a niche area, and the detailed assessment procedure has its own rules, conventions, and tactical dynamics.

---

Need Help With a Detailed Assessment?

Whether you are the receiving or paying party, Mackenzie Costs can handle the entire process for you, from drafting the bill through to advocacy at the SCCO hearing. As a Legal 500 ranked practice, we bring specialist expertise to every stage of the costs assessment process.

Related Specialist Support

Costs Budgeting and Detailed Assessment: Precedent H, dispute documents, negotiations and assessment strategy.
Costs Lawyer Support: Direct help with costs procedure, strategy, drafting and advocacy.
Bills of Costs: Clear, defensible traditional and electronic bills prepared for recovery.