Construction businesses in the UK face three accounting obligations that generic software handles poorly: CIS deduction management, domestic reverse charge VAT on construction services, and retention accounting. Purpose-built construction accounting platforms automate all three, alongside job costing and subcontractor payment runs. This guide covers the regulatory requirements and maps which platforms serve which firm size.
Last reviewed May 2026
Construction is one of the most administratively demanding sectors in the UK for financial management. A general contractor running multiple concurrent projects must track job costs against estimates, manage CIS deductions for subcontractors, handle the domestic reverse charge on VAT for qualifying services, account for retentions held by clients and paid to subcontractors, and produce project profitability reports that feed into contract decisions. General-purpose accounting platforms can handle some of these requirements with configuration, but the configuration overhead is significant and the risk of miscoding - particularly on VAT reverse charge - creates HMRC exposure. Purpose-built construction accounting software addresses these requirements as standard features, not workarounds.
CIS: The Construction Industry Scheme Requirements
The Construction Industry Scheme (CIS) requires contractors to deduct money from subcontractor payments and pass it to HMRC. The deduction rate is 20% for registered subcontractors, 30% for unregistered subcontractors, and 0% (gross payment status) for subcontractors who have demonstrated sufficient compliance history to qualify. HMRC's CIS guidance requires contractors to verify each subcontractor's status via the HMRC CIS online service before making the first payment, to deduct at the correct rate, and to file monthly CIS returns by the 19th of each month showing payments made and deductions withheld.
Subcontractors who have suffered CIS deductions can offset them against their own tax and National Insurance liability at year-end, or claim repayment if deductions exceed the liability. For subcontractors operating as limited companies, CIS deductions are offset against Corporation Tax and PAYE/NIC liabilities. The system creates significant cash flow implications for both parties: contractors must reserve the deduction amounts before paying subcontractors, and subcontractors must track deductions suffered to ensure correct recovery.
Accounting software that handles CIS must be able to: verify subcontractor status against the HMRC CIS online database (or prompt for manual verification); apply the correct deduction rate automatically when subcontractor invoices are posted; generate monthly CIS return data in the format required for HMRC submission; produce CIS deduction statements for subcontractors (required by law within 14 days of each monthly return); and reconcile the CIS liability account against monthly payments to HMRC. HMRC's detailed CIS guidance for contractors and subcontractors sets out the full obligations.
Domestic Reverse Charge VAT: The Construction Sector's Most Complex VAT Rule
The domestic reverse charge for construction services has applied since March 2021. Under the reverse charge, the VAT-registered customer (rather than the supplier) accounts for VAT on qualifying construction services. The supplier issues an invoice showing the net amount and stating that the reverse charge applies; the customer accounts for both the output VAT and the input VAT in their own VAT return. The supplier receives no VAT cash from the customer and does not include the transaction in Box 1 of their VAT return in the normal way.
The reverse charge applies to most standard and reduced-rate construction services supplied between VAT-registered businesses in the supply chain, but not to supplies made directly to end users (the property owner who will occupy the building) or to suppliers who are connected to the customer. The HMRC reverse charge guidance runs to considerable length and has generated significant compliance errors since introduction. The most common mistake is applying standard VAT on a transaction that should be reverse charged, or vice versa - both of which result in an incorrect VAT return and potential penalties.
Construction accounting software that handles the reverse charge natively applies the correct VAT treatment based on the customer's and supplier's VAT status and the nature of the supply, rather than requiring manual coding for each transaction. For contractors with high subcontractor invoice volumes, automated reverse charge handling materially reduces VAT return errors.
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Retention Accounting
Retentions are amounts withheld by clients from contractor payments - typically 3-5% of the contract value - as security against defects during a rectification period, usually 12 months after practical completion. Contractors similarly withhold retentions from subcontractor payments. The accounting challenge is that retentions are genuine receivables (money owed to the contractor) and genuine payables (money owed to subcontractors) that do not appear on the bank statement until the retention is released, often one to two years after the underlying work was performed.
Under RICS guidance on retentions in the construction industry, retentions held from subcontractors should ideally be held in a designated trust account, though this is not yet a statutory requirement in England (unlike Scotland, where the Housing Grants, Construction and Regeneration Act 1996 and subsequent Scottish legislation have moved further towards mandatory retention protection). The Retention (Construction Industry) deposit scheme proposed in England has been subject to ongoing consultation.
Construction accounting software must track retentions receivable and retentions payable separately from the main debtor and creditor ledgers, flag retentions due for release based on contract dates, and produce a retention schedule showing the total held and expected release dates. Generic bookkeeping platforms require manual workarounds (separate nominal codes, manual tracking spreadsheets) to achieve this - introducing reconciliation risk at year-end and audit.
Job Costing and Project Profitability
Job costing is the process of tracking all costs - labour, materials, plant hire, subcontractor payments - against a specific contract or project, and comparing actual costs to the original estimate or tender. For a construction business, job costing is the primary management information tool: it identifies which contracts are profitable, where cost overruns are occurring, and which project managers or trade teams are performing above or below estimate.
The strongest construction accounting platforms integrate job costing with the purchase ledger and payroll, so that subcontractor invoices, material deliveries, and labour costs are coded to the relevant job at the point of entry, not retrospectively. This real-time job cost view allows project managers to intervene before a contract runs significantly over budget, rather than discovering the overrun at final account stage.
| Platform | CIS | Reverse Charge VAT | Retentions | Job Costing |
|---|---|---|---|---|
| Sage 50 Construction | Yes | Yes | Yes | Yes |
| Xero + Tradify | Yes (Xero) | Yes (Xero) | Partial | Yes (Tradify) |
| QuickBooks + BigChange | Yes (QB) | Yes (QB) | Partial | Yes (BigChange) |
| Eque2 Construct | Yes | Yes | Yes | Yes |
| Coins (Construction Industry Solutions) | Yes | Yes | Yes | Yes - integrated with commercial management |
Platform Selection by Firm Size
Small contractors and sole-trader tradespeople - those with turnover below £500,000 and a handful of concurrent jobs - most often use Xero or QuickBooks as the accounting backbone, supplemented by a job management tool (Tradify, Jobber, or BigChange) that handles quoting, scheduling, and site documentation. The integration between the job management tool and the accounting platform handles invoice creation and cost coding, with the reverse charge and CIS handled within Xero or QuickBooks natively.
Mid-size contractors with turnover between £1 million and £20 million and 10-100 employees typically evaluate Sage 50 Construction or Eque2 Construct. Both platforms are purpose-built for the construction sector and handle CIS, reverse charge, retentions, and job costing without requiring third-party add-ons. Eque2 integrates with estimating software (including its own Eque2 Estimating product) to create a direct link between tender figures and job cost budgets.
Larger contractors and main contractors with turnover above £20 million and complex multi-entity structures typically run COINS (Construction Industry Solutions) or Viewpoint (now part of Trimble). These platforms handle multi-company consolidation, complex subcontract management with automated CIS and retention tracking, and integration with commercial management and quantity surveying functions. Implementation costs are significant - COINS and Viewpoint projects are typically six-figure implementations - but the operational savings on a large main contractor's subcontractor payment run justify the investment.
CIOB Guidance and Professional Standards
The Chartered Institute of Building (CIOB) publishes guidance on construction payment practices, including the requirements of the Housing Grants, Construction and Regeneration Act 1996 (as amended by the Local Democracy, Economic Development and Construction Act 2009). These Acts govern payment notice requirements, pay less notices, and the right to suspend for non-payment - all of which have accounting implications. Construction accounting software that generates payment notices and tracks notice periods against contract payment terms reduces the risk of inadvertent non-compliance with the statutory payment regime.
FAQ
What is the CIS deduction rate for unregistered subcontractors?
Contractors must deduct 30% from payments to subcontractors who are not registered under the CIS scheme. For registered subcontractors without gross payment status, the rate is 20%. Subcontractors with gross payment status receive payment in full, with no deduction. The status must be verified via HMRC's CIS online service before the first payment; re-verification is required each tax year.
Does the domestic reverse charge apply to all construction invoices?
No. The reverse charge applies to standard and reduced-rate construction services supplied between VAT-registered businesses in the construction supply chain where the recipient will use the service to make further onward supplies of construction services. It does not apply to supplies made directly to end users, to connected parties within a corporate group, or to supplies that are zero-rated or exempt from VAT. HMRC's guidance includes a detailed flowchart for determining whether the reverse charge applies.
Are retentions subject to VAT when released?
VAT on retentions follows the VAT liability of the underlying supply. Where the construction service was standard-rated, VAT applies to the retention amount when it is invoiced or paid - whichever is the tax point. Where the reverse charge applied to the main supply, it continues to apply to the retention release. HMRC's guidance on the tax point for retention payments is set out in VAT Notice 700.
Can Xero handle CIS as a standalone solution?
Xero includes CIS functionality for contractors and subcontractors, covering deduction rate application, monthly return data generation, and CIS deduction statements. It handles the domestic reverse charge natively. For small contractors with straightforward subcontractor arrangements, Xero is sufficient. Larger contractors needing retention tracking, detailed job costing, or subcontract management will typically need a specialist platform or a significant add-on stack alongside Xero.
What records must a contractor keep for CIS purposes?
Contractors must keep records of all payments made to subcontractors, the deduction amounts withheld, and the subcontractor's verification status for at least three years after the end of the tax year to which they relate. Monthly CIS return data and payment and deduction statements must also be retained. HMRC may inspect these records during a compliance check; construction accounting software that stores CIS transaction history in an auditable format significantly reduces the burden of such inspections.
How We Verified
This article draws on HMRC's Construction Industry Scheme guidance, HMRC's domestic reverse charge VAT guidance for building and construction services, RICS guidance on retentions, and the CIOB's payment practice resources. Vendor capability claims reflect publicly available product information as of May 2026. Platform tier classifications reflect observed market positioning in the UK construction sector. No vendor has paid for inclusion or editorial placement.
