Monthly CIS returns must be filed online with HMRC by the 19th of each month, covering payments made in the previous tax month.

Contractors must verify subcontractors' CIS status before making the first payment, using HMRC's online service or by phone.

Deduction rates apply: 20% for registered subcontractors, 30% for unverified ones, and 0% for those with gross payment status.

Subcontractors must provide their Unique Taxpayer Reference (UTR) and National Insurance number to contractors for verification.

Keep detailed records of all payments, deductions, and subcontractor details for at least three years after the tax year ends.

If no payments are made in a month, you still need to submit a nil return to HMRC to avoid penalties.

Use HMRC's CIS online service to file returns, make payments, and manage subcontractor registrations efficiently.

Penalties apply for late filing: £100 for one day late, with additional charges after three and six months, plus interest on late payments.

Subcontractors can claim back over-deductions through their Self Assessment tax return at the end of the tax year.

Businesses in Oldham and the UK must ensure their accounting software, like Xero or QuickBooks, is set up correctly for CIS compliance.