CIS Bookkeeping for UK Construction Subcontractors and Contractors

CIS bookkeeping is its own discipline. The Construction Industry Scheme operates on top of normal corporation tax, VAT, and PAYE for construction businesses, with monthly CIS300 returns, mandatory subcontractor verifications, and a specific deduction-and-recovery cycle that the rest of the UK tax system does not parallel. Add the post-2021 VAT Domestic Reverse Charge for construction services and the bookkeeping load doubles. This guide is the working manual for SME bookkeepers handling CIS clients.

CIS applies to contractors who pay subcontractors for construction work and to subcontractors who receive those payments. Most active construction SMEs are both: they receive payments from main contractors (as a subcontractor) and pay smaller subcontractors (as a contractor). The bookkeeping has to handle both sides without confusion.

Recording CIS deductions on the subcontractor side

When a subcontractor invoices a contractor for construction services:

• Contractor verifies the subcontractor with HMRC (online via the CIS service).
• Verification returns one of three rates: 20% (standard verified), 30% (unverified), or 0% (gross payment status).
• Contractor deducts the applicable rate from the labour portion of the invoice; materials are not deductible.
• Contractor pays the net amount; reports the gross + deduction on the monthly CIS300; issues a payment-and-deduction statement to the subcontractor within 14 days of the month end.

The bookkeeper's job on the subcontractor side: record the gross invoice value as revenue, the deduction as a CIS asset (recoverable from HMRC), and the net cash receipt as a bank deposit. Year-end, the subcontractor's CIS deductions are offset against PAYE/CT liability or refunded.

Recording CIS deductions on the contractor side

When the SME is the contractor paying subcontractors:

1. 1Verify every new subcontractor before first payment (CIS online service or via the agent portal).
2. 2Record the subcontractor's invoice gross; deduct CIS on the labour portion at the verified rate; pay net.
3. 3CIS deducted is a liability owed to HMRC (CIS Payable account in the GL).
4. 4Pay HMRC monthly by the 22nd of the following month.
5. 5File the monthly CIS300 return by the 19th of the month following the period.

Monthly CIS300 preparation workflow

CIS300 is due monthly even when no subcontractor payments were made (nil return required). The bookkeeper workflow:

• On or before day 5 of each month, list every subcontractor paid in the prior tax month (6th to 5th).
• For each subcontractor: name, UTR or NINO, gross paid (excluding materials), CIS deducted.
• Reconcile total deductions to the CIS Payable GL balance.
• Submit CIS300 via HMRC online or through CIS software (most cloud accounting platforms have native or integrated CIS handling).
• Pay the CIS deduction balance to HMRC by the 22nd.
• Issue payment-and-deduction statements to subcontractors within 14 days of the month end.

Gross payment status: the cash-flow reward

A subcontractor with gross payment status receives the full invoice value with no CIS deduction. Three qualifying tests:

• Turnover test: at least £30,000 of construction turnover per partner/director in the past 12 months.
• Compliance test: clean compliance history with HMRC across CT, VAT, PAYE, and CIS.
• Business test: genuine construction business operating from a UK business address.

HMRC reviews gross payment status annually; even one late return or payment can trigger removal. For a busy subcontractor invoicing £30k/month, gross payment status preserves £6,000/month of working capital that would otherwise sit with HMRC as CIS deductions awaiting refund.

The DRC VAT interaction with CIS

Since March 2021, construction services within the CIS scheme between two VAT-registered parties also fall under the VAT Domestic Reverse Charge. The interaction:

• Subcontractor invoice: shows CIS deduction (if applicable) AND notes "Reverse charge: customer to pay the VAT to HMRC."
• Subcontractor does NOT charge VAT on the invoice.
• Contractor records the supply with reverse-charge VAT (input AND output simultaneously, net zero).
• Bookkeeping treatment: separate GL accounts for DRC sales and standard-rate sales, separate tax codes in Xero/QuickBooks.

The combined effect on subcontractor cash flow is significant: no VAT charged (gone since 2021) and possibly 20-30% CIS deducted on labour. A busy subcontractor sees only ~50-60% of gross invoice value as cash on the day of payment, with the rest recoverable later.