The tax month is not the calendar month
A CIS tax month runs from the 6th to the 5th. Not the 1st to the 31st. It is a small thing that quietly ruins a return, because the two are close enough that nobody notices until HMRC does.
Pay a subcontractor on 3 June and it belongs in the month ending 5 June. Pay the same subcontractor on 6 June and it belongs in the month ending 5 July, a whole return later. Three days apart on the calendar, a month apart on the return, and the correction afterwards is an amended one.
That is why this asks for a payment date rather than a month. Give it the date and the right tax month falls out of it.
One date to remember, not two
The return is due by the 19th of the month following the tax month. The statements are due within 14 days of the end of the tax month. Those sound like two different deadlines and they are the same day: 5 June plus 14 days is 19 June, and the return for the month ending 5 June is due 19 June.
Every month of the year works out that way. So there is one date in the diary, the 19th, and everything for that month has to be done by it.
Paying nobody is not nothing to do
A month with no subcontractor payments still needs a return: either a nil return showing zero, or telling HMRC you have temporarily stopped using subcontractors. Nothing forces this one except forgetting to file it.
Miss it and the £100 penalty starts the day after the deadline, exactly as it would on a month where you paid thirty people. It escalates the same way too: £200 at two months, then £300 or 5% of the deductions at six months and again at twelve, whichever is higher. On a quiet month there are no deductions for the percentage to bite on, so it stays at the flat sum, which is small enough to be annoying and large enough to be avoidable.
The verification number is not a field you always fill in
A payment and deduction statement has to show the contractor's name and employer tax reference, the tax month ending date, the subcontractor's name and UTR, the gross paid excluding VAT, the materials, the amount liable, the amount deducted and what was payable.
And the verification number, only where the higher rate was applied because verification failed. That is the bit that gets done wrong in both directions: left off a statement that needs it, or printed on every statement as though it were part of the letterhead. This tool asks for one only when a subcontractor is on 30%, leaves it off the rest, and says so if a higher-rate row is missing it.
Why one file rather than thirty
Because a contractor with thirty subcontractors has thirty statements to issue and one set of figures to report, and doing that a statement at a time then adding it up by hand is how errors get in. One PDF: the return figures on the front, then a page per subcontractor to send out.
One thing this deliberately will not do is verify anybody. A subcontractor's status is whatever HMRC returns when you verify them for this contract, not what they told you, and not what it was last year. The rate on the screen is the rate you have been given, and the tool takes your word for it because it has no way not to.
Common questions
When is the CIS monthly return due?
By the 19th of the month following the tax month. A tax month running 6 May to 5 June has a return due by 19 June. Payment and deduction statements are due within 14 days of the tax month end, and since 5 June plus 14 days is also 19 June, both land on the same date.
What dates does a CIS tax month cover?
The 6th of one month to the 5th of the next, not the calendar month. Miss that distinction and a payment lands in the wrong return: a payment on 3 June belongs in the month ending 5 June, and a payment on 6 June belongs in the month ending 5 July, a whole return later.
Do I have to file if I paid no subcontractors?
Yes. Either file a nil return showing zero, or tell HMRC you have temporarily stopped using subcontractors. The £100 penalty starts the day after the deadline whether or not there was anything to report, and a forgotten nil return costs you that penalty for nothing.
What are the CIS late filing penalties?
£100 at one day late, £200 at two months, then at six months and again at twelve months it is £300 or 5% of the deductions on the return, whichever is higher. Beyond twelve months it can reach £3,000 or 100% of the deductions. The percentage only starts to bite on bigger returns.
What has to be on a payment and deduction statement?
The contractor's name and employer tax reference, the tax month ending date, the subcontractor's name and Unique Taxpayer Reference, the gross amount paid excluding VAT, the cost of materials, the amount liable to deduction, the amount deducted and the amount payable. Plus the verification number, but only where the higher rate was applied.
When does the verification number go on the statement?
Only where you deducted at the higher rate because verification failed. It is not a field to fill in every time. Printing it on every statement puts information on the document that HMRC expects only in that one situation, and this tool leaves it off the others and tells you when it is missing from one that needs it.