CIS compliance software for contractors

Three rates, chosen from the subcontractor’s verified tax treatment.

• If the subcontractor is not verified, the rate is 30% regardless of what treatment is stored against them.
• A CIS worker paid through timesheets with no matching subcontractor record is treated as unverified and deducted at 30%.

On labour only. The deduction base is the total payment less materials, less VAT, less plant hire and less other allowable exclusions.

• Excluded amounts are still paid in full — they are removed from the base, not from the payment.
• The other-exclusions bucket covers items such as the CITB levy and fuel.
• The base is floored at zero, so exclusions larger than the payment can never produce a negative deduction.
• Where hours come from timesheets, entries categorised as plant go to plant hire and other to the other-exclusions bucket; everything else is labour.

NoteThe materials, VAT and plant figures come from what is entered on the payment. Estimark does not read a subcontractor’s invoice and split it for you.

Yes, when HMRC is connected — it is a real call to HMRC’s CIS verification endpoint, against either the sandbox or the production service.

• A match returns the verification number and the tax treatment, which are stored against the subcontractor.
• No match returns higher-rate treatment, so the subcontractor is deducted at 30%.
• With no HMRC connection, Estimark refuses the verification and tells you to connect HMRC or record the verification number HMRC gave you. It never fabricates one.
• A verification number obtained by phone or through HMRC’s own service can be recorded manually, with its date and treatment.

A CIS tax month runs from the 6th of one month to the 5th of the next. Tax month 1 is 6 April to 5 May.

• The tax period is derived from the payment date, so a payment on the 3rd falls into the previous period automatically.
• The return for a period is due by the 19th of the month that period ends in — the return for 6 April to 5 May is due 19 May.
• Periods are labelled in full, for example “06 Apr – 05 May 2026”, so nobody has to interpret a month number.
• An unsubmitted return past its due date is flagged overdue.

No. Estimark records the filing; it does not transmit it. Filing requires user-restricted HMRC OAuth and fraud-prevention headers, which Estimark does not implement.

• Generating a return pulls every unlinked deduction for that tax period and locks it to the return.
• Totals are gross payment, deductions, and materials including plant and other exclusions.
• A period with no deductions is marked as a nil return automatically.
• Marking the return submitted requires both statutory declarations: that no contract included is a contract of employment, and that every subcontractor has been verified or appeared on a return in the current or previous two tax years. Without both, Estimark refuses.
• You record how it reached HMRC — the reference, the method and the date — so the audit trail is complete.

A payment and deduction statement as a PDF, per subcontractor, covering a tax year.

• It carries the contractor name and UTR, the subcontractor’s UTR, verification number and tax treatment, and a row per deduction with gross, rate, deduction and net.
• The footer cites the Income Tax (Construction Industry Scheme) Regulations 2005.
• A CIS CSV export gives you hours, total payment, plant hire, other exclusions, the labour deduction base, rate, deduction and net payment per subcontractor.

NoteYou download the statement and send it. Estimark does not email statements automatically, and does not send CIS deadline reminders.