Every contract bills differently, and that is the whole problem #
A cleaning business with thirty contracts usually has something close to thirty billing arrangements. Not thirty prices, thirty arrangements. The variation is in the shape rather than the number.
-
Fixed monthly in advance, or fixed monthly in arrears
Which sounds trivial until a contract starts or ends mid month.
-
Fixed plus variable
The core clean is fixed, periodic work and call outs are billed as done.
-
Per site or per contract
One client with eleven buildings may want one invoice, eleven invoices, or one invoice broken down by site with a separate cost centre each.
-
Purchase order numbers
Required per invoice, per site, per line, or reissued each quarter, and an invoice without one is returned unpaid.
-
Consumables
Included, billed at cost, billed on a schedule, or excluded and forgotten.
-
Deductions and service credits
Agreed in the contract, applied by the client, argued about later.
-
Portal or email
Larger clients require submission through their own system, with their own fields and their own rejection rules.
None of these is complicated on its own. Thirty of them, held in one person's head and a folder of contract documents, is a job that cannot be delegated and cannot be done quickly.
The variable part depends on paperwork you do not have yet #
The fixed element could be invoiced on the first of the month without anybody thinking. The variable element cannot, because it depends on facts that live on site: which periodic tasks were completed, which call outs happened, how many hours the extra cover actually took, whether a deep clean was signed off.
So the invoice run waits on site sheets coming back, which is the slowest and least reliable input in the business. The record is created at the furthest point from the office by the person with the least reason to care about it, and until it arrives the invoice cannot be raised. Every day of that delay is a day added to the front of the payment clock.
Because labour is most of the cost, the arithmetic is unforgiving. With the National Living Wage at £12.71 an hour for workers aged 21 and over from 1 April 2026, hours captured wrongly or late translate directly into margin.
What the invoice has to carry #
GOV.UK sets out the minimum.
- A unique identification number
- Your business name, address and contact details
- The customer's name and address
- A clear description of what is being charged for
- The date the service was provided, and the invoice date
- The amounts, the VAT if applicable, and the total owed
In this sector the rejections are almost never about the total. They are about the description and the dates, because a facilities manager approving an invoice needs to match it to a site, a period and a purchase order, and a line reading "cleaning services, September" across eleven buildings gives them nothing to approve.
When it becomes late, and what you are entitled to #
Where nothing else has been agreed, payment is late 30 days after the client receives the invoice or you provide the service, whichever is later. Agreed business to business terms should not exceed 60 days unless a longer period is fair to both businesses, and for public authorities the default is 30 days, which matters in a sector with a lot of school, council and NHS work.
If it goes late, the entitlements are set out in legislation.
8%
Statutory interest, plus the Bank of England base rate, on business to business transactions
GOV.UK, Charging interest on a commercial debt
£40
Fixed recovery costs on debts up to £999.99
GOV.UK, Claim debt recovery costs on late payments
£70
Fixed recovery costs on debts of £1,000 to £9,999.99
GOV.UK, Claim debt recovery costs on late payments
£100
Fixed recovery costs on debts of £10,000 or more
GOV.UK, Claim debt recovery costs on late payments
Those fixed sums are chargeable once per payment, alongside reasonable costs of recovery. Very few cleaning businesses charge any of it, which is a commercial choice rather than a legal one, but it is worth making deliberately rather than by default.
Which parts run on rules #
Runs on rules
- Raising the fixed element from an agreed schedule
- Applying each contract's own billing shape and breakdown, once the shape is written down
- Pro rating a contract that started or ended mid month
- Chasing the site records the variable element depends on. The trigger is their absence
- Checking a purchase order number is present and current
- Producing a description the client can actually approve
- Flagging an invoice that has passed its terms
Needs a person
- Deciding whether to bill a disputed extra at all
- Deciding whether to accept a client's service credit
- Deciding whether to charge statutory interest to a client you want to keep
What to measure #
Three numbers for one quarter.
- How many working days the invoice run takes, from the first of the month to the last invoice out
- How many of those days were spent waiting on site paperwork rather than doing anything
- How many invoices were queried or returned, sorted by reason
The third list is short and repetitive, and it usually points at description and purchase order fields rather than at anything about the cleaning. The chasing payment tool prices the delay, and the billing shapes that cause it were agreed back when the contract was quoted.