Deduct CIS when you pay a subcontractor

Open the subcontractor's record and check it is the party you actually contracted with: the trading name, the company registration and the subcontract they are working under. This is the record the deduction is taken against.

Why: A deduction is taken from a party, not from an invoice, and on a job with three companies inside one group the invoice does not always tell you which one is which. Getting the party right first is what makes everything after it checkable.

Install the Construction Industry Scheme for the United Kingdom and record this subcontractor's standing under it: the band they are entitled to, whether gross payment, standard or higher, the verification reference the authority gave, and the dates that verification covers.

Why: The band is only as good as the verification behind it, and verifications expire. Holding the reference and the dates on the record means the rate applied to a payment can be justified months afterwards, which is precisely when somebody asks about it.

Preview the deduction against the gross payment. The scheme decides what comes out of the taxable base, so the materials element and the VAT are handled by the scheme rather than by whoever happens to be doing the sum, and a band that depends on a verification is only kept while that verification still holds.

Why: A party who has lost their verification drops to the scheme's highest band, and the preview reports the drop rather than quietly applying it. A rate that went up because a certificate lapsed is a conversation to have before the remittance, not after the subcontractor has read it and rung the commercial manager.

Determine whether the domestic reverse charge applies to this supply. It covers construction services reported under the scheme between VAT registered businesses, and it stops at the end user, who accounts for VAT the ordinary way.

Why: The reverse charge moves the VAT from the supplier to the customer, so an invoice raised the old way is wrong on its face and the customer cannot simply pay it and move on. Determining it per supply, and keeping the determination, is what keeps a subcontractor's invoice payable on the day it arrives.

Report the deductions taken in the period: who they were taken from, the gross, the materials, the amount deducted and the verification each band rested on. That is the substance of the monthly return and of the statement every subcontractor is entitled to receive.

Why: The return is due every month whether or not the paperwork was kept, and reconstructing a month of deductions from bank payments is how a small error turns into a penalty. A report built from the recorded deductions carries the same facts as the subcontractor's own statement, which is why the two agree without anybody negotiating.