Accounting and invoicing for structural engineers
Structural design, checks, surveying and reports: engineering firms bill by work stage, hours and flat fees and work for architects, developers and authorities. Saldiqo issues stage invoices, records time per project and reminds on long payment terms.
What comes up for structural engineers
Stages and hours
Structural design is billed in stages, reports and checks by effort.
Long payment terms
Developers and authorities often pay after 30 to 60 days.
Software and equipment
Structural software, surveying equipment and licences are big items.
How Saldiqo helps
- Stage invoices per phaseQuote, stage invoices, final invoice.
- Time trackingRecord and bill effort per project.
- RemindersKeep open invoices in view.
Typical invoice lines
Examples that often appear on invoices in this industry. You set the prices yourself.
- Structural design detached house, stage invoice 1 of 3
- Stability check, hours
- Survey of existing building, flat fee
- Report by effort
- Site visit, travel
- Software licence as per receipt
Tax and invoicing in the UK
What applies to invoices in the UK, in short. As of October 2026.
- VAT
- Standard rate 20 %, reduced rate 5 % and zero rate 0 %. Saldiqo calculates each invoice line with the rate you pick.
- VAT registration
- You must register once your taxable turnover passes £90,000 over any 12 months, or you expect to pass it within the next 30 days. You can deregister below £88,000. Until you are registered, your invoices show no VAT, and Saldiqo adds up your 12-month turnover for you.
- What goes on an invoice
- If you are VAT registered: your VAT number, the tax point, unit prices and the VAT total in pounds. A limited company shows its registered name on every invoice, and its company number, registered office and part of the UK on letters, order forms and the website.
- E-invoicing
- There is no mandate today. From April 2029 e-invoicing is planned for all B2B and B2G sales that carry VAT, through Peppol. The exact date and standard are not yet in law, and the government’s roadmap follows with the Budget on 28 October 2026.
- VAT returns
- VAT returns go to HMRC through Making Tax Digital, usually quarterly, due one month and seven days after the period. Saldiqo shows sales and VAT per rate and exports CSV. It does not submit to HMRC, and for Making Tax Digital you need software recognised by HMRC.
- Record keeping
- Keep VAT records for 6 years.
- Late payment
- Statutory interest on late business payments is the Bank Rate (3.75 % in the second half of 2026) plus 8 points, so 11.75 %. On top comes fixed compensation of £40, £70 or £100, depending on the amount owed (under £1,000, from £1,000, from £10,000). Consumers have no statutory interest.
- Getting paid
- Your sort code and account number are on every invoice. Customers pay by Faster Payments or Bacs, and banks check the account name with Confirmation of Payee. There is no QR standard in the UK.
Frequently asked questions
How do I bill planning services?
With stage invoices per phase and hours for reports and checks.
Can I evaluate time per project?
Yes. Time tracking and a cost centre per project.
Do structural engineers in the UK have to charge VAT?
Only once they are VAT registered. Registration is required when taxable turnover passes £90,000 over any 12 months, or is expected to within the next 30 days. Below that you may register voluntarily. If you are not registered, you must not show VAT on your invoices.
Do structural engineers in the UK need e-invoicing?
Not today. A mandate for B2B and B2G sales with VAT is planned from April 2029, and the details were still open as of October 2026. You can keep sending PDF invoices for now.
How long should structural engineers keep invoices?
Keep VAT records for 6 years. You can store receipts digitally in Saldiqo. The legal duty to keep records stays with you.
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As of October 2026. General information, not legal or tax advice, without guarantee. For your case ask your tax adviser.