What UK government contracts 30-day payment terms really mean in practice

Winning a public sector contract can feel like a major victory for any UK small business. The work is often meaningful, the budgets are real, and there’s an assumption of reliability. The government, after all, is the ultimate blue-chip client. A key part of that promise is the legal requirement for public bodies to pay their suppliers within 30 days.

For many businesses, however, the gap between this 30-day promise and the reality of getting paid can be a frustrating chasm filled with bureaucracy, confusing payment portals, and a maddening hunt for the correct Purchase Order number. This article cuts through the noise to explain what the public sector payment rules really are, why they often fail in practice, and what you can do to ensure your invoices are paid promptly.

The Official Position: 30-Day Payments Are the Law

Unlike the private sector, where payment terms can be a point of negotiation, the rules for the public sector are far more rigid and are enshrined in law. This isn't just a guideline; it's a legal obligation.

The key piece of legislation is The Public Contracts Regulations 2015. Regulation 113 specifically states that every public contract must include a term requiring the contracting authority to pay any valid and undisputed invoice within 30 calendar days.

This applies to the vast majority of public sector bodies, including:

• Central government departments (e.g., Ministry of Defence, Department for Education)
• Local authorities (councils)
• NHS Trusts and other health bodies
• Police and fire authorities
• Universities and further education colleges

The clock starts ticking from the moment the public body receives what it deems a "valid invoice". This is a critical detail. A simple error, a missing piece of information, or sending it to the wrong inbox can render your invoice "invalid" in their eyes, stopping the 30-day clock before it has even started.

This 30-day rule is a significant protection for suppliers. For standard business-to-business transactions in the private sector, the default payment period under late payment law is 60 days unless a shorter period is agreed upon. The public sector is held to a higher, faster standard.

The Prompt Payment Code: A Commitment, Not an Iron-Clad Guarantee

You will often hear the Prompt Payment Code (PPC) mentioned in the same breath as public sector payments. While related, it's important to understand the distinction between the PPC and the legal requirement set out in the Public Contracts Regulations.

The Prompt Payment Code is a voluntary scheme administered by the office of the Small Business Commissioner. Signatories to the code make a public commitment to good payment practices. The core commitments are:

• To pay 95% of all invoices within 60 days.
• To pay 95% of invoices from small businesses (those with fewer than 50 employees) within 30 days.
• To work towards adopting 30 days as the norm for all suppliers.

Thousands of companies are signatories, including almost all central government departments and many major government contractors. Being a signatory is often a prerequisite for bidding on large central government contracts.

However, the key word is "voluntary". The main penalty for failing to meet the PPC's standards is suspension or removal from the list of signatories. While this is a reputational blow, it doesn't have the same immediate legal force as the Public Contracts Regulations. It's a powerful tool for encouraging a culture of prompt payment, but your legal right to be paid in 30 days comes from the Regulations, not the Code.

Why Do Public Sector Payments Get Delayed? The Reality on the Ground

If 30-day payment is the law, why are so many small businesses still waiting 45, 60, or even 90 days for their money? The issue rarely stems from a lack of funds. Instead, it's almost always a breakdown in process.

The Purchase Order Is King

In the public sector, no Purchase Order (PO) number often means no payment. A PO is the internal document that authorises the expenditure. Without it, the accounts payable (AP) department literally has no budget code to assign your payment to. They are not permitted to pay an invoice that doesn't correspond to an approved PO. Many SMEs get caught out by starting work on a verbal say-so, only to find their invoice is rejected weeks later because a PO was never raised.

Departmental Silos

The person who commissioned your work and is delighted with the result is almost never the person who processes your invoice. Your contact might be in the marketing, operations, or IT department, while your invoice goes to a centralised, anonymous AP or finance department, often in a different building or city. If your invoice doesn't have every single piece of information the AP team needs, they won't chase the marketing manager for it; they will simply reject it or let it sit in a query queue.

Incorrect Invoice Details

Public sector finance systems are notoriously rigid. A tiny error can cause an invoice to be rejected automatically. Common mistakes include:

• Wrong Entity Name: Invoicing "The local council" instead of the precise legal name, e.g., "Anytown Borough Council".
• Wrong Address: Using the address of the department you worked with, not the official finance department address for invoices.
• Missing Information: Forgetting to include your bank details, company number, or VAT number.
• No Contact Name: Failing to include the name of the person who commissioned the work.

Complex Approval Chains

Even with a valid PO and a perfect invoice, payment can be held up by internal approval workflows. An invoice for a significant amount might need to be signed off by two or three different managers. If one of those individuals is on annual leave or off sick, the process grinds to a halt. There is often no system for a deputy to approve payments in their absence.

Your Toolkit for Getting Paid: A Practical Step-by-Step Guide

You cannot change public sector bureaucracy, but you can navigate it effectively. Getting paid on time requires a proactive and meticulous approach from the very beginning.

Step 1: Pre-Emptive Action (Before You Invoice)

The work you do before you even issue the invoice is the most important part of getting paid promptly.

• Get the PO Number: Do not start work without a written Purchase Order number. Make this a non-negotiable part of your process.
• Confirm the Details: Ask for the full, correct legal name of the public body you are contracting with.
• Find the Right Inbox: Confirm the exact email address or portal for invoice submission. Never assume it goes to your day-to-day contact. Ask them: "Who in your finance team should I send the invoice to, and can you provide their direct email address?"
• Check Formatting Rules: Ask if their system requires invoices in a specific format (e.g., PDF only) or has any other quirks.

Step 2: Submitting the Perfect Invoice

Your invoice must be a perfect, self-contained document that requires zero investigation from the AP clerk.

• Prominent PO Number: Put the Purchase Order number at the top of your invoice where it cannot be missed.
• Full Details: Include your full company name, address, company number, and VAT number (if applicable).
• Their Full Details: Use the exact legal entity name they provided.
• Clear Line Items: Provide a clear, simple description of the goods or services supplied, matching the description on the PO.
• Bank Details: Triple-check that your bank name, account number, and sort code are correct.

Once sent, consider a polite follow-up a few days later to your main contact, CC'ing the finance address: "Just a quick one to confirm you've received our invoice [Invoice Number] and that it's in the system for payment." This simple check can save weeks of waiting.

Step 3: The Waiting Game and When to Chase

Diarise the 30-day deadline from the date your invoice was successfully submitted. Do not wait until day 45 to start chasing. Your first follow-up should be on day 31.

Keep the initial tone friendly and helpful. "Hi team, I'm just following up on invoice [Invoice Number] for £X, which was due for payment yesterday. Could you please provide an update on its status? A copy is attached for your convenience."

Manually tracking and chasing dozens of invoices is time-consuming. Tools like InvoiceReminder can automate this process, sending scheduled follow-ups for you so nothing slips through the cracks, whether your client is a local council or a private business. This ensures a consistent, professional approach without the manual effort.

Step 4: Escalation (When Polite Chasing Fails)

If you receive no response or a vague answer, it's time to escalate. On your next follow-up, around day 35-40, be firmer and reference the law.

Your email should now include phrases like:

• "As a reminder, under the Public Contracts Regulations 2015, payment for this invoice was legally due within 30 days."
• "Please be aware that we are entitled to claim statutory interest and compensation for late payment under the Late Payment of Commercial Debts (Interest) Act 1998."

At this stage, it's also worth picking up the phone. Try to get past the gatekeeper and speak to someone in the AP department directly. A human conversation is often more effective than a dozen emails.

Claiming Statutory Late Payment Interest and Compensation

When a public sector body pays you late, you are legally entitled to charge them interest and a fixed compensation sum. This is not being difficult; it's your statutory right under The Late Payment of Commercial Debts (Interest) Act 1998.

The amount you can claim is broken into two parts:

1. Statutory Interest: This is calculated at 8% plus the Bank of England's base rate. For example, if the base rate is 5.25%, the annual rate you can charge is 13.25%. You would then calculate this on a daily basis for the number of days the payment is overdue.
2. Fixed Compensation: This is a one-off sum you can claim for each late invoice to cover the cost of chasing the debt. The amount is set by law and depends on the value of the invoice.

Debt Value	Compensation Amount
Up to £999.99	£40
£1,000 to £9,999.99	£70
£10,000 or more	£100

When you decide to claim, send a revised invoice or a statement of account that clearly shows the original amount, the late payment interest calculated to date, and the fixed compensation fee.

Some businesses worry this will damage their relationship with the client. While this can be a concern with smaller private clients, public sector AP departments are generally so detached from the commissioning side that they treat it as a procedural matter. Invoking your statutory rights is often the fastest way to get your invoice moved to the top of the pile.

Last Resorts: The Small Business Commissioner

If you have followed all the steps above and are still facing a wall of silence, your final port of call before considering legal action is the Small Business Commissioner (SBC).

The SBC's office can investigate complaints about late payment issues with larger businesses (including public bodies) that are signatories to the Prompt Payment Code. They can make recommendations and use their influence to resolve disputes. This is a free service and can be a powerful ally for a small business struggling against a large, unresponsive organisation. You should only approach them after you have made reasonable attempts to resolve the issue yourself.

Frequently asked questions

What's the most common reason a public sector invoice is paid late?

Missing or incorrect Purchase Order (PO) numbers are the single biggest cause of delays. Without a valid PO, the invoice often gets stuck in a queue and cannot be processed by the public body's finance system. Always secure a PO number in writing before starting any work.

Can I really charge a government department for paying me late?

Yes. The Late Payment of Commercial Debts (Interest) Act 1998 applies to public sector bodies just as it does to private companies. You are legally entitled to claim statutory interest (currently 8% plus the Bank of England base rate) and a fixed compensation sum of £40, £70, or £100 depending on the invoice value.

Is the 30-day payment rule for public sector contracts absolute?

Yes, for undisputed invoices, it's a legal requirement under the Public Contracts Regulations 2015. The 30-day clock starts from the moment the public body receives a 'valid' invoice. The main reason for non-payment within this timeframe is if the invoice is disputed or deemed invalid due to missing information.

What is a 'valid invoice' in the eyes of a public sector body?

A valid invoice is one that contains all the information their finance system needs to process it without any manual queries. This always includes your full company details, their full legal entity name, a valid PO number, a clear breakdown of charges, and correct bank details. Any error or omission can lead to rejection.

Does the Prompt Payment Code guarantee I'll be paid in 30 days?

No. The Prompt Payment Code is a voluntary commitment, not a law. While signatories are expected to pay 95% of their small business invoices within 30 days, your ultimate legal protection comes from the Public Contracts Regulations 2015 and your statutory rights under the Late Payment Act.

Should I stop work if a public sector client hasn't paid me?

This is a commercial decision. While you may have the right to suspend services for non-payment, it can be a risky move that could jeopardise the future relationship. It's generally better to exhaust all chasing and escalation options, including claiming statutory interest and involving the Small Business Commissioner, before taking such a drastic step.

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