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CIS Monthly Subcontractor Statements

Example prompt: "On the 6th of each month at 9am, pull every payment we made last month to subcontractors tagged 'CIS' from Xero, grouped by subbie. For each, look up their CIS verification status from our 'Subcontractors' Google Sheet (gross, net at 20%, or higher rate at 30%) and apply the correct deduction to the labour portion only — never to materials. Draft a CIS Payment and Deduction Statement in Google Docs for each subcontractor showing gross labour, materials, deduction rate, deduction amount, and net paid for the period. Save each statement in the 'CIS Statements' Google Drive folder under the subbie's name and tax month. Draft an email in Gmail to each subbie with their statement attached — do not send. Build a one-page summary document listing total payments, total deductions, and the figures we will need for the monthly CIS300 return, and post it in #accounts on Slack with links to all the statement drafts so I can review the batch before sending."

The Problem

The Construction Industry Scheme is one of those bits of UK admin that is straightforward in principle and slow in practice. Every month we pay subcontractors, deduct tax at the right rate, give each one a statement by the 19th, and file a CIS300 return that has to match. Getting the labour-versus-materials split wrong, or the verification status, or missing a subbie off the return, lands fines that compound. The owner-operator usually ends up doing this on a Sunday morning with a spreadsheet and a calculator.

How GloriaMundo Solves It

We build a scheduled workflow that runs on the 6th of each month. An integration step pulls last month's subcontractor payments from Xero. A code step groups them by subcontractor, separates labour from materials using the bill line categories, and looks up each subbie's verification status from a Google Sheet to pick the right deduction rate. An LLM step generates the standard CIS Payment and Deduction Statement for each subbie in Google Docs. An integration step files each statement in the right Drive folder and drafts an email to the subcontractor with the statement attached. A final code and LLM pair builds the monthly summary with the totals we need for the CIS300, and posts it in Slack for review. Glass Box preview shows every statement and every figure before anything is sent or filed.

Example Workflow Steps

  1. Trigger (scheduled): At 9am on the 6th of each month.
  2. Step 1 (integration): Pull every paid bill from Xero in the previous tax month from contacts tagged 'CIS', with line-level labour and materials breakdown.
  3. Step 2 (code): Group by subcontractor, sum labour and materials separately, and look up each subbie's verification status from the 'Subcontractors' Google Sheet to determine the deduction rate (gross 0%, net 20%, higher 30%).
  4. Step 3 (code): Apply the deduction rate to the labour portion only and calculate the net amount paid for the period.
  5. Step 4 (llm): Generate a CIS Payment and Deduction Statement for each subcontractor using our standard template — gross labour, materials, deduction rate, deduction, net.
  6. Step 5 (integration): Save each statement to the 'CIS Statements' Google Drive folder under the subbie's name and tax month.
  7. Step 6 (integration): Draft an email in Gmail to each subcontractor with their statement attached, leaving it as a draft.
  8. Step 7 (llm + integration): Build a one-page summary with totals and the figures needed for the CIS300, and post it in #accounts on Slack with links to every statement draft.

Integrations Used

  • Xero — source of subcontractor payments split by labour and materials
  • Google Sheets — the subcontractor register with verification status and deduction rate
  • Google Docs — the per-subbie CIS statements
  • Google Drive — the 'CIS Statements' folder by month
  • Gmail — the per-subbie covering email, held as a draft
  • Slack — the batch review and CIS300 summary

Who This Is For

UK construction firms registered as contractors under CIS who pay subcontractors monthly, who currently produce statements by hand or with a spreadsheet, and who would rather review a batch of drafts on the 6th than build them from scratch on the 18th in a panic before the 19th deadline.

Time & Cost Saved

Producing a CIS statement by hand takes ten to fifteen minutes per subcontractor once we have looked up the verification status, separated labour from materials, and calculated the deduction. With five to ten subbies a month that is one and a half to two and a half hours. The CIS300 totals on top take another half hour. This workflow turns the whole monthly job into a thirty-minute review, and the audit trail in Drive and the summary in Slack make the HMRC return a copy-paste rather than a recalculation. The bigger saving is not the late-filing fine we will never get.