You have built a 12-person digital agency billing £800,000 a year. You have a retainer book that covers your overheads. Your team is strong. You are ready to sell.

Then the buyer asks for three years of financial statements, management accounts, and a breakdown of gross margin by client. And suddenly, the deal feels fragile.

Due diligence is where agency sales happen. It is also where they fall apart. Most of the time, the problem is not the agency itself. The problem is the financials were never set up for a buyer to read.

Here is exactly how to prepare financials due diligence agency sale processes demand. Clean accounts, clear margins, and the three statements buyers actually check.

Why Due Diligence Kills Agency Deals

Buyers are looking for risk. Every number they see is a test. If your financials are messy, they assume your operations are messy too.

Common deal-breakers we see at Agency Founder Finance include:

  • Directors' loan accounts that have not been cleared for years
  • Gross margins that fluctuate wildly between months with no explanation
  • Contractor costs lumped into "other expenses" instead of tracked as direct costs
  • No management accounts produced for the last 12 months
  • VAT returns that do not match the P&L

None of these are fatal if caught early. But if a buyer's due diligence team finds them in week three of a six-week process, you lose use. The purchase price gets adjusted. Or the buyer walks.

The fix is simple: prepare before the process starts.

The Three Statements Buyers Actually Check

A buyer will ask for everything. But they focus on three documents. Get these right and you solve 80% of due diligence problems.

1. Three Years of Filed Accounts

This means your statutory accounts filed at Companies House. They must be clean. No late filing penalties. No inconsistencies between the filed numbers and your internal records.

If you have ever filed abbreviated accounts (which hide turnover and cost of sales), you need to switch to full accounts for at least the last two years before sale. Buyers cannot assess your agency without seeing revenue and gross profit.

Check your filed accounts now. If the numbers do not match what you tell the buyer in the information memorandum, you start the conversation with a credibility gap.

2. Last 12 Months of Management Accounts

Buyers want to see monthly P&L, balance sheet, and cash flow statements. They want to see trends. Is revenue growing month on month? Are margins stable? Is your cash position improving or deteriorating?

If you do not produce management accounts, start now. Use Xero or QuickBooks with Spotlight Reporting or Float to generate them monthly. A buyer will not trust an agency that cannot produce basic internal financials.

Your management accounts should show:

  • Revenue by client and by service line
  • Gross margin (revenue minus direct staff and contractor costs)
  • Overhead breakdown by category
  • Net profit margin
  • Cash balance and debtor days

3. A Clean Balance Sheet

Most agency founders focus on the P&L. Buyers focus on the balance sheet. Because that is where the hidden liabilities live.

Key items to clean up:

  • Directors' loan account. If you owe the company money, clear it before due diligence starts. If the company owes you, take it as a dividend or director's loan repayment. An overdrawn DLA is a red flag for buyers and can trigger a section 455 tax charge at 33.75% if not repaid within nine months of year end.
  • Debtors. Aged debt over 90 days needs a provision. Buyers will discount it. Chase old invoices or write them off before the process starts.
  • Creditors. HMRC arrears are a deal-killer. Pay your corporation tax, VAT, and PAYE on time. If you have a time-to-pay arrangement, disclose it early.
  • Intercompany balances. If you have multiple companies (a trading company and a property company, for example), clear the balances or document them formally.

Gross Margin: The Metric That Makes or Breaks Your Valuation

Your agency's gross margin is the single most important number in a sale. It tells the buyer how profitable your core service delivery is.

Calculate it as:

Gross Margin (%) = (Revenue - Direct Costs) / Revenue x 100

Direct costs include:

  • Salaries for billable staff (account managers, creatives, developers, strategists)
  • Freelancer and contractor costs
  • Software tools used directly on client projects (Adobe Creative Cloud, Figma, etc.)
  • Third-party costs passed through to clients

For a healthy UK agency, gross margin should sit between 50% and 65%. Below 45% and buyers will question your pricing. Above 70% and they will wonder if you are underinvesting in delivery.

If your gross margin is inconsistent month to month, add a note explaining why. Seasonal patterns, project mix changes, or one-off large contracts all create variance. Buyers accept variance if you explain it. They do not accept unexplained noise.

Revenue Quality: Retainers vs Projects

Buyers pay a premium for predictable revenue. Retainer income is worth more than project income because it is recurring.

Break your revenue into three categories:

  • Retainers: Monthly recurring contracts with 30-day notice periods or longer
  • Project work: One-off engagements with defined scope and timeline
  • Pass-through costs: Media spend, print, third-party licences you bill through without markup (or with low markup)

Buyers typically apply a multiple to your maintainable EBITDA (earnings before interest, tax, depreciation, and amortisation). If 60% of your revenue is retainer-based, your EBITDA multiple will be higher than if 60% is project-based.

Show this breakdown clearly in your information pack. Do not make the buyer's team dig for it.

EBITDA Adjustments: What Buyers Add Back

Buyers calculate your maintainable EBITDA by adjusting your reported profit for one-off costs and owner-related expenses. This is where agency founders often leave money on the table.

Common add-backs include:

  • Your salary above market rate. If you pay yourself £120,000 but a replacement managing director costs £80,000, the buyer adds back £40,000.
  • Discretionary bonuses. Bonuses to staff that are not part of a formal scheme can be adjusted if the buyer does not plan to continue them.
  • Personal expenses. Cars, travel, entertainment, and other costs run through the company for your benefit.
  • One-off legal or professional fees. Costs related to the sale process itself (advisory, legal, due diligence support).
  • Related party transactions. Rent paid to a property company you own. Management fees to a holding company.

Document every add-back with evidence. If you claim your car lease is a personal expense, have the lease agreement ready. If you claim a bonus is discretionary, show the board minute authorising it.

As ICAEW qualified accountants, we see deals where poor add-back documentation costs founders £50,000 to £100,000 in reduced valuation. Do not let that be you.

Debtor Days and Cash Flow

An agency that collects its cash quickly is worth more than one that does not. Buyers calculate debtor days (also called days sales outstanding or DSO) to assess your cash conversion.

Calculate it as:

Debtor Days = (Trade Debtors / Annual Revenue) x 365

For a healthy agency, debtor days should be below 45. Above 60 and you have a collection problem. Above 90 and buyers will assume some of that debt is uncollectable.

If your debtor days are high, take action before the sale process:

  • Implement 30-day payment terms if you have not already
  • Chase overdue invoices aggressively
  • Consider invoice factoring or discounting to clean up the balance sheet (but disclose it)
  • Write off genuinely uncollectable debts

Contractor Costs and IR35

If you use contractors, a buyer will want to see your IR35 compliance. The buyer is taking on the liability for any historic IR35 errors.

You need to show:

  • Status Determination Statements (SDS) for each contractor engagement
  • Evidence that you ran the CEST tool or took professional advice
  • Confirmation that contractors are paid through an umbrella company or your own PAYE scheme where required
  • A clean record of no HMRC enquiries into your contractor arrangements

If you have contractors you treat as outside IR35 but the engagement looks inside (long-term, integrated into the team, using your equipment, taking direction from your managers), a buyer will either discount your price or require an indemnity.

Fix this before you go to market. Read our guide on IR35 compliance for agency contractors for the full process.

Tax Compliance: The Non-Negotiable

Buyers will check your tax history. They want to see that you have filed everything on time and paid everything you owe.

Key items to prepare:

  • Corporation tax returns (CT600) for the last three years, with HMRC acknowledgement
  • VAT returns (VAT100) for the last three years, with payment evidence
  • PAYE and RTI submissions for the last two years
  • P11D forms for benefits in kind
  • R&D tax credit claims if you have made them, with supporting technical reports
  • Any HMRC correspondence including open enquiries or time-to-pay arrangements

If you have an open HMRC enquiry, disclose it upfront. Do not let the buyer find it through their own checks. A disclosed enquiry is manageable. A hidden one is a deal-breaker.

The Due Diligence Data Room

Buyers expect a virtual data room with organised files. Do not dump everything into one folder. Structure it logically.

Recommended folder structure:

  • Financials: Filed accounts, management accounts, budgets, forecasts
  • Tax: Corporation tax, VAT, PAYE, R&D claims
  • Revenue: Top 10 clients, retainer agreements, project pipeline
  • Costs: Staff costs, contractor agreements, supplier contracts
  • Legal: Articles of association, shareholder agreements, key contracts
  • People: Staff list, employment contracts, share scheme documents
  • Property: Lease agreements, service charge statements

Use a platform like DealRoom, Ansarada, or even a well-organised Google Drive with permissions. The easier you make it for the buyer's team, the faster the process runs.

When to Start Preparing

Start at least 12 months before you plan to sell. Ideally 18 to 24 months.

Why so early? Because some fixes take time. You cannot clear a directors' loan account overnight if you do not have the cash. You cannot change your contractor arrangements in a week. You cannot build a 12-month track record of clean management accounts in two months.

The agencies that sell at the best multiples are the ones that treat the sale process like a marathon, not a sprint. They clean up their financials, document everything, and present a business that a buyer can understand and trust.

If you want to talk through your agency's financial position before you go to market, get in touch with the team at Agency Founder Finance. We work exclusively with agency founders and we know what buyers look for.