What to collect before adding a new subcontractor

What a contractor should collect and check before adding a subcontractor to its supplier list: tax numbers by country, papers, bank details and red flags.

By Achekam · 11 October 2026 · 4 min read · For Construction businesses in South Africa, Nigeria, Kenya

The site needs a tiling team on Monday. The site agent has found one through a friend of the foreman, and wants them paid at the end of their first week. By Friday afternoon the office has a name, a cellphone number and a bank account copied from a WhatsApp message, and a payment going out.

That is how most supplier fraud on building sites starts: not with a sophisticated scheme, but with a rushed onboarding nobody checked. A few minutes of checks before a subcontractor is added to your supplier list protects your money, your tax position and your site. This article sets out what to collect in South Africa, Nigeria and Kenya, and how Achekam helps.

One supplier list and its duplicate check by name or VAT number

Achekam keeps one supplier list for the business, with duplicate checks by name or VAT number. Quotations, purchase orders and bills all pick suppliers from it. That matters for two reasons. First, the same subcontractor working on three jobs is one record, with one history of claims, payments and retention. Second, the duplicate check catches the classic trick of a second record for the same business with different bank details.

Before adding anyone, search the list for their trading name, their registered name and their tax number. If the duplicate check flags a match, stop and find out why before going further.

Tax numbers by country: VAT number, Nigeria Tax ID or KRA PIN

Collect the subcontractor's tax identity, and check it at the authority, not just on their letterhead:

• South Africa: the VAT number, if they are registered for VAT, and their income tax reference. If their quotation adds VAT, make sure the VAT number on it is real before you accept a tax invoice from them.
• Nigeria: since 1 January 2026, Nigeria issues a 13-digit Tax ID that replaces previously issued TINs, through the national Tax ID portals. Companies retrieve theirs with their CAC registration number. Every taxable person must obtain one and show it on returns and transaction documents. Ask for the Tax ID, not an old TIN.
• Kenya: the KRA PIN. Achekam checks only a PIN's shape, a letter, nine digits and a letter, as a soft check. Confirm the PIN on iTax's PIN checker and keep the evidence with the supplier's file.

Nigerian and Kenyan VAT numbers the supplier screen still refuses

One limit to know about: a supplier's VAT number must currently be in the South African format, so Nigerian and Kenyan VAT numbers are refused on the supplier screen. Nigerian and Kenyan contractors should not invent a number to get past the check. Record the supplier without it, and keep the real number on the signed onboarding form and in the supplier's folder in Documents until the screen follows your country.

Registration papers and insurance certificates filed in Documents

Ask for the papers that show the subcontractor is a real, registered business able to do the work:

• company or business-name registration certificate;
• proof of tax status: a tax clearance or compliance certificate where your country issues one;
• the contractor registration or grading their trade or your client requires;
• workers' compensation or employer's liability cover, where the law requires it;
• public liability insurance, with the policy period;
• a bank confirmation letter, on the bank's letterhead, for the account they want paid into.

File them in Document Centre, which lets a business upload files or whole folders, tag and search them, and keeps earlier versions when a new one is uploaded. Make one folder per subcontractor, and tag each document with its expiry date, so a lapsed insurance certificate is found before an accident rather than after.

Bank details and the warning signs the integrity review raises

Bank details are where fraud bites. Take them only from a bank confirmation letter, and confirm them by phoning the subcontractor on a number you already have, not the one in the e-mail that sent them. Do the same every time a subcontractor says its bank details have changed. The ICAEW's guide on how to identify and deal with fake invoices explains the warning signs, such as mismatches with purchase orders and delivery notes, and preventive controls like segregation of duties and verifying bank-detail changes.

Achekam's procurement integrity review, sold as its own add-on, raises questions about warning patterns such as competing quotes sharing contact or bank details, or a supplier paid into an employee's bank account. Those two are exactly the patterns a "friend of the foreman" arrangement can produce. One caution: its check for purchases split under a threshold does nothing until a threshold is set, which the app cannot do yet. Non-profits use the same review on their grants and purchases; the procurement integrity review explains it from their side.

A short onboarding checklist for the site office

Print this and make it the condition for any first payment:

1. Search the supplier list by name and tax number; no duplicate.
2. Tax number collected and checked at the authority, with evidence filed.
3. Registration certificate, tax status, insurance and any trade registration filed and tagged with expiry dates.
4. Bank confirmation letter on file, and bank details confirmed by phone on a known number.
5. Subcontract terms agreed: rates, retention, payment terms and who measures the work.
6. Supplier added by the office, not by the person who will approve their claims.
7. Onboarding form signed by the site agent and checked by someone in accounts.

Before the first claim

Once the subcontractor is on the list, their first claim goes through the order-measure-match routine described in approving a subcontractor's progress claim, and the retention you hold from them is recorded as shown in recording retention you hold back from subcontractors. Start by running your existing subcontractors through the checklist, beginning with the ones paid most often.

General guidance only, not advice on your own circumstances. Tax and payroll rules change: check the current position with the authority or your adviser.