Clearing an invoice backlog: catching up on months of unbilled work

To clear an invoice backlog, list every finished job you haven't billed, sort the list by value and age, and invoice the top five first, ideally the same day. Use the date the work finished as the supply date, send each invoice with a short catch-up email, and set a due date. Most firms can bill a two-month backlog in one focused day.

Why does an invoice backlog build up?

Because invoicing happens after the job, when you're already on the next one. The work is done, the customer is happy, and the paperwork waits for an evening that never comes.

That's not unusual. A renovation builder we work with described his admin as "a bit of a shambles" before he cleared a week's backlog in under 24 hours. The pile always looks bigger than it is until it's on one list.

How do you find every job you haven't billed?

Work from evidence, not memory. Go through each source below for the backlog period and write one line per job: customer, site, date finished, rough value.

If your supplier bills are in Xero or a capture tool, match them to jobs as you go. It's the quickest way to spot work you forgot, and it gives you the materials figure for each invoice. See Dext alternatives for trades if your bills aren't in one place yet.

Which invoices should you send first?

Bill the jobs worth the most first, then the oldest. A big invoice that's two months late costs you more in cash than five small ones, and the older a job, the harder it is to remember the extras.

Within each invoice, list the work plainly, include any agreed extras, and attach photos if the job was weeks ago. A customer who can see the finished wall pays faster than one squinting at "works as discussed".

What date goes on a late invoice?

Two dates: the invoice date is today, and the supply date is when the work finished. GOV.UK says every invoice must show both, along with a unique number, your details, the customer's details, a clear description, the amount and the total owed.

So if you're VAT-registered and a backlog runs across a VAT quarter end, some of that VAT may belong in the quarter you've already filed or are about to file. Tell your accountant before you send the batch, not after. If a deposit was paid, the deposit usually created its own tax point when it was received. Building work paid in stages works differently: each stage's tax point is usually the earlier of the payment or the VAT invoice, not the date the work finished, so check those jobs with your accountant too.

What do you say to customers who are getting a late bill?

Keep it short and confident. One line of explanation, the invoice, a due date, and how to pay. Customers rarely mind a late bill for good work; they mind a confusing one.

Subject: Invoice invoice number for job, e.g. bathroom refit at 12 Mill Lane

Hi customer name,

Apologies for the delay getting this over. Please find attached invoice invoice number for short description of the work, finished on date work finished.

Total: £amount including VAT / no VAT charged
Less deposit paid on [date: £deposit]
Amount due: £balance
Due by: due date, e.g. 14 days from today

You can pay by bank transfer to account name, sort code sort code, account account number, using invoice number as the reference.

If anything on it doesn't match what we agreed, reply here and I'll sort it the same day.

Thanks again for the work,
your name
business name, phone

For business customers, a payment is legally late 30 days after they receive the invoice if no date was agreed, so give a due date. For overdue ones afterwards, follow how to chase an unpaid invoice.

How long do you have to send an old invoice?

Longer than most owners fear. In England and Wales, a claim on a simple contract can be brought up to six years after the cause of action arose, so an invoice sent three months late is still owed. That doesn't make it wise: the later the bill, the more likely the customer disputes extras or has spent the money.

Scotland's time limit for most debts is five years. If a large or disputed sum is involved, get advice from a solicitor before you send it.

How do you stop the backlog coming back?

Invoice on the day the job finishes, from the van, while the details are fresh. That needs three things in place:

1. An invoice template you can send from your phone.

   Xero, QuickBooks and most invoicing apps do this. If it takes a laptop, it'll wait.

2. A job list that shows "finished, not invoiced".

   Whether that's a spreadsheet column or software, someone needs to see it daily. A per-job invoice tracker does this for commercial work.

3. Deposits and stage payments on bigger jobs.

   You can't fall months behind on a job that bills at each stage. See deposits and stage payments.

4. A fixed weekly slot.

   Thirty minutes every Friday to bill anything finished that week and chase anything overdue.

Common questions