Invoicing App for Gas Engineers: How to Bill Letting Agents and Landlords Without Chasing (UK, 2026)
Agent and landlord invoices stall when the property or payer is missing. What the invoice must carry, why it should leave with the gas safety record, and five checks to run on any invoicing app.
Updated 1 November 2026
TLDR: For letting agent and landlord work, the invoice must carry the property, the payer and the job reference, and leave with the gas safety record from one job record. Choose an invoicing app by how it holds the payer and the property, not by its invoice templates, and test it on a three-property agent day first.
Picture six landlord gas safety visits for one agent in a day. Six records sent by teatime. Then, a fortnight later, an email from the agent’s accounts team: they can’t pay, because the invoice doesn’t say which property it covers. The work was done, the paperwork reached the right inbox, and the money still hasn’t moved.
It’s an easy problem to miss when you choose an app by its invoice templates. On rented property, the person who pays usually isn’t the person who let you in, and the payment tends to fail on a missing property or payer detail rather than on the look of the invoice. So the app has to hold the payer and the property properly, and send the invoice out with the record it relates to.
Who is the customer on a rented property job?
The customer is whoever you agreed the work with, and on rented property that’s usually the landlord or the letting agent, not the tenant at the door. Agents are a big part of this market. In the government’s English Private Landlord Survey 2024, about 2.9 million of the 4.2 million live tenancy deposits in England (70%) were registered by agents on behalf of landlords.
Who holds the gas safety duty depends on the paperwork between them. The Health and Safety Executive’s guidance on who counts as a landlord says the management contract should spell out who is responsible for gas safety checks and record keeping. If it names the agent, the agent carries the landlord’s duties. If it’s unclear, the duties stay with the landlord.
What must the invoice show, compared with the record?
The invoice must name the customer; only the gas safety record must name the property. GOV.UK says an invoice must show the name and address of the customer you’re invoicing, a description, the supply date, a unique number and the amounts. For VAT invoices, HMRC’s VAT Notice 700, section 16.3 asks for the name and address of the person you supplied. Neither asks for the address where the boiler sits.
The gas safety record does. Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 requires the record to include the address of the premises and the name and address of the landlord or, where appropriate, the agent.
| Detail | Gas safety record | Invoice |
|---|---|---|
| Property address | Required by regulation 36 | Not required by law; the agent needs it to pay |
| Landlord or agent | Name and address required | Name and address of the customer you invoice |
| Agent’s job reference or PO | Not required | Include it whenever the customer issues one |
That middle column is where agent invoices go wrong. The law is satisfied by the agent’s office address, but the agent’s accounts team can’t match a payment to a landlord without the property. The Small Business Commissioner’s invoicing guidance makes the same point from the payer’s side: the person who commissions work may not be the person who handles payment, and a needed purchase order number should be requested early.
What should you agree with the agent before the first job?
Settle four things in writing before the first job: who you’re contracting with, whose name goes on the invoice, which inbox it goes to, and whether they issue a job reference or purchase order. Agree payment terms at the same time. Where no payment date is agreed, GOV.UK says a business payment is late 30 days after the customer gets the invoice or you provide the service, whichever is later.
Why should the invoice leave with the gas safety record?
Because the payer is remote, the invoice has to explain itself, and the simplest way to do that is to send it with the record it relates to. When both documents come from one job record, they share the same property, the same landlord or agent and the same date. Nobody types the address twice, so the two can’t disagree.
The agent’s office also gets one email that answers both questions at once: was the check done, and what do we owe? Our guide to sending a gas safety record and keeping proof of delivery covers the handover itself, including what to check before sending and why a sent email isn’t proof the file was opened. The Schmitdy Trades film Best CP12 App UK: Prove Gas Safety Delivery explains what that delivery trail should hold: who received the record, the contact used and when it was sent.
In Checker, the invoice starts from the finished report. One tap copies the line items across, and the report and invoice can go out attached to the same email, as our quotes and invoices page sets out (checked 1 November 2026). A record still supports competent work rather than proving compliance, and the landlord’s duties to the tenant don’t move to the engineer because the email went out.
One job record, one send: how an agent job should flow
- 1Job recordProperty, payer, agent reference, terms
- 2Gas safety recordPremises address and landlord or agent, from the job
- 3InvoiceSame property, payer and reference, no retyping
- 4One email to the payerRecord and invoice attached together
- 5Chaser until paidReminders after terms lapse, stopped by payment
Takeaway: type the property and payer once, at the job record. Every document after that inherits them.
What does a six-property agent day need from the app?
A batch day needs the app to hold one payer with several properties under it, so each record and invoice picks up the right address without retyping.
Illustration, not a real job. Assumptions, set on 1 November 2026 for the arithmetic only: one letting agent, six rented houses, one landlord gas safety check at each, an assumed price of £70 plus VAT per check, VAT at 20%.
6 checks × £70 = £420. VAT at 20% = £84. Total £504.
Typed separately, the six property addresses go into six records and six invoice lines: 12 entries, each a chance for a typo. From one job record per property, it’s six entries.
Before that day, ask the agent one question: one invoice per property, or one for the day? Some agents settle each job from that landlord’s funds and want them separate. Others prefer one bill.
On PRO and PRO+, our customer database stores every property under one customer, each with its own appliance list, report history and service reminders (checked 1 November 2026). For each automatic message, you choose whether it goes to the client, usually the person paying, to the contact at the property, to yourself, or a mix. That’s set in the Preferences tab, described on our automations page.
The agent’s own job reference is the detail to test in any app before you rely on it. Find out where a reference or purchase order number sits on the invoice, and whether it prints where the accounts team will look. If there’s no dedicated field, put it at the start of the description line so it can’t be missed.
How do you get paid without the phone call?
You get paid without ringing round when the invoice carries an easy way to pay and reminders reach the payer on their own.
- A way to pay on the invoice. Our invoices can carry a Pay Now card link through Stripe, including Apple Pay and Google Pay, with bank details on the PDF for transfers (checked 1 November 2026).
- Chasers that stop themselves. The invoice chaser sends up to three reminders once the payment terms run out, on days you can change, and stops when the invoice is marked paid.
- Payments back in your books. On PRO and PRO+, Checker synchronises invoices and payments both ways with Xero, as our Xero sync guide explains, and also connects to QuickBooks and Sage.
If a payment still goes quiet, our guide to chasing overdue trade invoices without losing the customer sets out a tone that keeps the agent’s future work.
You also have legal backing on business work. The Late Payment of Commercial Debts (Interest) Act 1998 applies where both sides act in the course of a business, which covers a letting agency. Whether a private landlord counts is worth checking rather than assuming. Where the Act applies and your contract sets no other rate, statutory interest is 8% plus the Bank of England base rate, and you can add a fixed recovery sum of £40, £70 or £100 depending on the debt. On the £504 illustration above, that fixed sum would be £40.
Which five questions test an invoicing app for agent work?
Run these on a real agent day with at least three properties before you pay for any app.
- Can one customer hold several properties? Add the agent or landlord once, then each property under them with its own records. Checker does this on PRO and PRO+.
- Does the invoice show the property as well as the payer? Raise a test invoice and look at the PDF. The payer’s address satisfies the law; the property address is what gets it paid.
- Where does the agent’s reference go? Find the field for a job reference or purchase order number and check it prints clearly. If there isn’t one, use the first words of the description.
- Do the record and invoice come from one job and leave together? Finish a gas safety record, create the invoice from it and send both in one email without retyping the address.
- Do reminders reach the payer and stop when paid? Check who receives the chaser, that payment stops it, and that the payment lands in your accounts software.
Checker covers questions 1, 4 and 5 on PRO and PRO+. We don’t advertise a dedicated purchase order field or show how the property appears on an agent’s invoice PDF, so run questions 2 and 3 on a free trial before you rely on us for agent work.
Our guide to invoicing and quoting software for plumbers and gas engineers compares named tools if you want a shortlist to test. Plans start at £10.99 a month for LITE, with PRO at £19.99 and PRO+ at £25.99, all plus VAT, and there’s a free trial without card details on our pricing page. The customer database, reminders and accounts sync sit on PRO and PRO+, so test those plans for agent work.
If you’re a sole trader doing mostly domestic jobs where the person at the door pays, a simple invoicing app is enough. If you already run Xero, its own invoicing app lets you invoice from your phone, take online payments and send reminders. The agent-ready record earns its keep once agent work passes a handful of properties a month.
Frequently asked questions
Should I invoice the landlord or the letting agent?
Invoice whoever you agreed the work with, and confirm that in writing before the first job. On a VAT invoice, HMRC expects the name and address of the person you supplied. If the agent instructs you but the landlord is your customer, agree whose name goes on the invoice and where it is sent.
Can I charge late payment interest to a letting agent?
Usually, yes. The Late Payment of Commercial Debts (Interest) Act 1998 applies where both parties act in the course of a business. If your contract sets no other rate, statutory interest is 8% plus the Bank of England base rate, plus a fixed recovery sum of £40, £70 or £100.
Does sending the record to the agent cover the tenant’s copy?
Not by itself. Regulation 36 requires the landlord to give existing tenants a copy within 28 days of the check, and new tenants before they move in. If the landlord or agent asks you to send the tenant a copy, record that instruction against the job.
How long should I keep agent invoices?
If you are self-employed, GOV.UK says to keep business records for at least 5 years after the 31 January submission deadline of the relevant tax year. The landlord keeps the gas safety record under regulation 36, but keeping your copy with the invoice makes later queries quicker to answer.
Do the same record rules apply in Northern Ireland?
Northern Ireland has its own Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004. Regulation 36 there also requires the landlord to give existing tenants a copy of the record within 28 days of the check. The invoicing rules above are UK-wide.
Authoritative sources
- MHCLG: English Private Landlord Survey 2024, main report.
- HSE: who counts as a landlord, including letting and managing agents.
- GOV.UK: invoices, what they must include.
- HMRC: VAT guide, VAT Notice 700, section 16 on VAT invoices.
- Gas Safety (Installation and Use) Regulations 1998, regulation 36.
- Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004, regulation 36.
- Small Business Commissioner: getting invoices right.
- GOV.UK: when a business payment becomes late.
- GOV.UK: interest on late commercial payments.
- GOV.UK: claiming debt recovery costs on late payments.
- Late Payment of Commercial Debts (Interest) Act 1998, section 2.
- GOV.UK: how long to keep self-employed business records.
- Xero UK: sending invoices from the Xero app.
- Video: Best CP12 App UK: Prove Gas Safety Delivery, Schmitdy Trades, YouTube.
Will your next agent invoice pass?
Run the five questions on your next agent invoice, then decide whether your current tool passes. If it fails two of them, try the same day in Checker.