Invoice Generator

Invoicing Tips for Plumbers

Getting paid on time is one of the biggest challenges for self-employed plumbers. Late payments affect your cash flow, your ability to buy materials for the next job, and your stress levels. Professional invoicing is the first step to getting paid faster and more reliably.

What Must an Invoice Include?

As a sole trader or limited company, your invoices must include certain information to be legally valid. This includes: a unique invoice number (sequential), your business name and contact details, the customer's name and address, the invoice date and due date, a clear description of the work carried out, the amount due with any VAT shown separately, and your payment details.

If you're VAT registered, you must also show your VAT number, the VAT rate applied, and the total VAT amount. If you're not VAT registered, it's good practice to note this to avoid confusion.

When to Invoice

Invoice as soon as the job is complete — ideally the same day. Every day you delay sending an invoice is a day you delay getting paid. For larger jobs that span multiple days or weeks, consider progress invoicing: invoice for agreed milestones (e.g., 30% on start, 40% at first fix, 30% on completion). This keeps cash flowing and reduces your risk.

Setting Payment Terms

Standard payment terms for plumbing work are 14 to 30 days from the invoice date. Shorter terms (7-14 days) are appropriate for smaller residential jobs, while 30 days is more common for commercial or insurance work. Make your payment terms clear on every invoice and discuss them before starting work.

Consider offering multiple payment methods — bank transfer, card payment, and even cash for smaller jobs. The easier you make it to pay, the faster you'll get paid. Some plumbers offer a 2-3% early payment discount for invoices paid within 7 days, which can significantly improve cash flow.

Chasing Late Payments

Despite your best efforts, some customers will pay late. Have a systematic approach: send a friendly reminder the day after the due date, follow up with a firmer reminder a week later, and escalate to a final demand after 30 days overdue. Under the Late Payment of Commercial Debts (Interest) Act 1998, you can charge interest on late payments from businesses at 8% above the Bank of England base rate.

The best approach is to automate this entire process. AI tools like Sidekick can send payment reminders automatically at the right intervals, saving you the awkwardness and time of chasing payments manually. Automated reminders are consistent, timely, and don't carry the emotional baggage that personal chase messages do.

Record Keeping

HMRC requires you to keep records of all sales and income for at least 5 years. This means storing copies of every invoice you issue. Using a digital system makes this simple — every invoice is stored, searchable, and ready for your accountant at tax return time. Paper-based systems work but are prone to loss and much harder to search through when HMRC comes knocking.

Under Making Tax Digital (MTD), sole traders with income above £50,000 will need to keep digital records and submit quarterly updates to HMRC. Getting your invoicing digital now will make this transition seamless.