Construction tax compliance - how CIS, VAT, CITB, and PAYE work together

Construction businesses face multiple overlapping tax obligations when paying for labour and services. Understanding how CIS, VAT, CITB, and PAYE work together helps you comply correctly and avoid costly mistakes.

This guide shows how these four systems interact on the same payment, with worked examples you can apply to your own business.

The four construction tax obligations

When you pay subcontractors or employ workers in construction, you may need to deal with all four of these systems:

• CIS (Construction Industry Scheme) - tax deductions from payments to subcontractors, paid to HMRC
• VAT reverse charge - construction services between VAT-registered businesses where the customer accounts for VAT
• CITB levy - training levy based on your total labour payments (PAYE wages + net CIS payments)
• PAYE - income tax and National Insurance for employees (not subcontractors - but employment status matters)

The key challenge is that these systems overlap but are not identical. A payment to a subcontractor may involve CIS, VAT reverse charge, and CITB simultaneously. Getting any one of them wrong creates compliance risk.

How CIS and VAT reverse charge interact

When you pay a VAT-registered subcontractor for construction services, both CIS deductions AND the VAT reverse charge may apply to the same payment. Understanding how these interact is essential for correct accounting.

The key principles:

• CIS applies to labour - deductions are calculated on the labour element only, not materials
• VAT reverse charge means no VAT on invoice - the customer accounts for VAT on their VAT return instead
• CIS is calculated on the net (pre-VAT) amount - the reverse charge does not change CIS calculations
• Both systems are linked through CIS reporting - the reverse charge applies to specified services reportable within CIS where the customer is CIS-registered (or required to be); the supplier does not need to be CIS-registered, but both parties must be VAT-registered

Key points from the worked example

The example above shows several important interactions:

1. CIS only applies to labour - the 2,000 materials are paid in full, only the 10,000 labour element has the 20% CIS deduction
2. No VAT appears on the invoice - the reverse charge means the contractor handles VAT accounting, not the subcontractor
3. Contractor pays 12,000 total - 10,000 to subcontractor + 2,000 CIS to HMRC
4. VAT is neutral for most contractors - Box 1 equals Box 4 if fully taxable

How CIS relates to CITB levy

The CITB levy is a statutory training levy collected from construction employers. Your CIS payment data directly feeds into your CITB levy calculation, but at a higher rate than PAYE wages.

Understanding this connection helps you budget correctly and explains why using more subcontractors increases your CITB costs.

Why subcontractor payments cost more in CITB levy

The worked example shows that net CIS payments attract a levy rate of 1.25% compared to 0.35% for PAYE wages. This is because:

• Subcontractors may not receive employer-funded training
• The higher rate compensates CITB for this training gap
• It incentivises contractors to invest in training or use trained subcontractors

Practical implication: When comparing the cost of using employees versus subcontractors, factor in the higher CITB levy rate on subcontractor payments.

CIS registration does NOT determine employment status

This is one of the most important - and most misunderstood - aspects of construction tax compliance. Being CIS-registered does not make someone self-employed.

CIS is purely a tax collection mechanism. A worker can be:

• CIS-registered AND genuinely self-employed - correct treatment
• CIS-registered AND actually an employee - compliance breach
• Not CIS-registered AND an employee - use PAYE

Getting this wrong exposes you to:

• Unpaid employer and employee National Insurance
• Employment tribunal claims for holiday pay, unfair dismissal
• Pension auto-enrolment failures
• Interest and penalties from HMRC

Worked example: All four obligations on one payment

Here is a complete example showing how CIS, VAT, CITB, and employment status checks all apply to a typical subcontractor payment.

Scenario

You are a main contractor paying a subcontractor for plastering work:

• Labour charge: 5,000
• Materials supplied by subcontractor: 500
• Both parties are VAT-registered and CIS-registered
• Subcontractor is registered (20% deduction rate)
• Your annual CIS payments will total 300,000
• You have verified the subcontractor's status

Step 1: Check employment status (before any payment)

Use HMRC's CEST tool to confirm the worker is genuinely self-employed, not an employee. Consider:

• Can they send a substitute?
• Do you control how they do the work?
• Do they work for other contractors?

If actually employed: Stop - use PAYE, not CIS.

Step 2: Calculate CIS deduction

• CIS applies to labour only: 5,000
• Deduction at 20%: 5,000 x 20% = 1,000
• Materials (no CIS): 500

Step 3: Apply VAT reverse charge

• Both parties VAT and CIS registered - reverse charge applies
• Invoice shows: 5,500 (no VAT)
• Annotation: "Reverse charge: Customer to account for VAT to HMRC"

Step 4: Calculate payment to subcontractor

• Gross invoice: 5,500
• Less CIS on labour: -1,000
• Pay subcontractor: 4,500

Step 5: Your accounting entries

• Pay subcontractor: 4,500
• Pay HMRC (CIS): 1,000 (by 22nd of following month)
• VAT return Box 1: 1,100 (reverse charge: 5,500 x 20%)
• VAT return Box 4: 1,100 (input VAT recovery)
• Net VAT effect: Zero (if fully taxable)

Step 6: CITB levy impact

The payment to a net-paid subcontractor counts towards your CITB levy at its value before the CIS deduction and excluding materials (payments to gross-paid subcontractors are not levied):

• Levy base: 5,000 (the labour payment gross of the CIS deduction; the 500 materials element is excluded)
• Added to your annual CIS total for levy calculation
• At 1.25% rate: 5,000 x 1.25% = 62.50 annual levy impact

Summary: Your total cost for this 5,500 invoice

• Payment to subcontractor: 4,500
• CIS to HMRC: 1,000
• VAT: 0 net (reverse charge offsets)
• CITB levy contribution: 62.50
• Total cost: 5,562.50

Common mistakes when these systems interact

CIS + VAT mistakes

• Applying CIS to materials: Only labour is subject to CIS deductions - materials pass through at full value
• Charging VAT when reverse charge applies: If both parties are CIS and VAT registered, no VAT should appear on the invoice
• Applying CIS to VAT amount: CIS is always calculated on the net (pre-VAT) labour amount

CIS + PAYE mistakes

• Assuming CIS registration = self-employed: Employment status is determined by the nature of the relationship, not CIS registration
• Using CIS for regular workers: If someone works set hours, uses your tools, and cannot send a substitute, they may be an employee
• Ignoring IR35: Limited company contractors may still be "inside IR35" requiring PAYE treatment

CITB mistakes

• Forgetting CIS attracts higher levy: Budget for 1.25% on subcontractor payments, not 0.35%
• Excluding CIS payments from levy return: CITB uses your CIS return data - your figures must match

Timeline: When each obligation triggers

Understanding the timing helps you stay compliant:

Before first payment to a subcontractor

• Verify CIS status: Check with HMRC online service
• Assess employment status: Use CEST tool, keep records
• Confirm VAT status: Check if reverse charge applies
• Get end user confirmation: If reverse charge may not apply, get written confirmation

When you make a payment

• Deduct CIS: Calculate on labour element
• Issue payment statement: Within 14 days of tax month end
• Account for VAT: On your VAT return (reverse charge)

Monthly deadlines

• CIS return: By 19th of following month
• CIS payment: By 22nd if paying electronically

Annual deadlines

• CITB levy return: Confirm PAYE and CIS figures
• CITB levy payment: Per assessment (can be spread)

Checklist: Integrated construction tax compliance

Use this checklist for each new subcontractor relationship:

Before engaging the subcontractor

• Verify their CIS registration status with HMRC
• Assess employment status using CEST tool and document result
• Check their VAT registration status
• Determine if VAT reverse charge applies (both CIS registered, not end user)
• If they claim end user status, get written confirmation

For each payment

• Separate labour from materials on invoice
• Apply correct CIS deduction rate to labour only
• Check invoice shows reverse charge annotation (if applicable)
• Issue payment and deduction statement

Monthly

• Submit CIS return by 19th showing all payments and deductions
• Pay CIS deductions to HMRC by 22nd
• Include reverse charge VAT in your VAT return

Annually

• Review employment status of regular subcontractors
• Complete CITB levy return accurately
• Pay CITB levy as assessed

Related guides

• Register as a CIS contractor - how to register with HMRC before making your first subcontractor payment
• VAT reverse charge for construction - detailed guidance on when and how the reverse charge applies
• Calculate CIS deductions - step-by-step guide to calculating the correct deduction amount
• Submit your CIS monthly return - how to file your CIS300 return correctly
• CIS registration does not determine employment status - why CIS does not make someone self-employed