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The admin deadlines a small trade business actually has to hit
Most tax content is written for accountants. This is the version for someone who is on the tools all day and does the paperwork at nine at night.
Two things carry automatic penalties and catch people out. Neither moves for weekends or bank holidays.
CIS: the 19th, every month, no exceptions
If you pay subcontractors for construction work, you file a CIS return every month.
Due the 19th. The date does not shift for weekends or bank holidays. Source: HMRC CIS guidance, checked 7 August 2026
£100 the day it is late. Then £200 at two months, and it escalates from there. Source: HMRC penalty guidance, checked 7 August 2026
Nil returns are mandatory again. Since 6 April 2026, a month with no subcontractor payments still needs a return. That is the one that gets people — a roofer rained off in February still has to file the month he had least reason to remember. Source: HMRC CIS guidance, checked 7 August 2026
Deductions are 20% for registered subcontractors and 30% for unregistered, so the money is material as well as the penalty.
CIS is wider than people expect. It covers building work, alterations, repairs, decorating, groundwork, landscaping, demolition and installing heating, lighting, air conditioning and CCTV.
Making Tax Digital: quarterly, and it has started
MTD for Income Tax brings sole traders and landlords over the threshold into quarterly digital updates rather than one annual return.
The practical change is not the tax. It is that your records have to be kept digitally and submitted through compatible software four times a year instead of being assembled once in January.
If you have been keeping receipts in the van and sorting them at year end, that is the habit that has to change, and changing it in a hurry the week before a deadline is how mistakes happen.
What actually goes wrong
In our own research into what UK trades struggle with, the pattern is consistent and it is not ignorance of the rules. It is that the admin happens after a nine-hour day.
The deadline is not usually missed because nobody knew. It is missed because Tuesday was busy, then Wednesday was, and by the 20th the £100 has already landed.
Where software helps, and where it does not
Software will not file for you unless you have kept the records. What it can do is stop the date arriving unannounced and stop the records being scattered.
LoopSuite's Accountant Pack Preparer gathers your records into one pack for your accountant, and Renewal Reminder tracks confirmed recurring dates and warns you before they lapse. Both land paused until you switch them on.
Being straight about the limit: we are not an accountant and this is not tax advice. Get the position confirmed by someone qualified.
Questions
When is the CIS return due?
The 19th of every month. The date does not move for weekends or bank holidays, and a £100 penalty applies from one day late.
Do I need to file a CIS return if I paid no subcontractors?
Yes. Nil returns became mandatory again on 6 April 2026, so a month with no payments still needs a return.
What counts as construction work for CIS?
More than most people expect — building, alterations, repairs, decorating, groundwork, landscaping, demolition, and installing heating, lighting, air conditioning and CCTV.
How much is deducted under CIS?
20% for registered subcontractors and 30% for unregistered ones.
Is this tax advice?
No. It is a plain-English summary of published HMRC deadlines. Get your own position confirmed by someone qualified.
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