Who this is for: UK developers, main contractors, and subcontractors who want zero-drama compliance—and a clear plan if HMRC raises a CIS penalty or threatens Gross Payment Status (GPS).
Why it matters: CIS penalties stack quickly (starting at £100 after 1 day late) and can escalate to 5% of deductions (or more for deliberate failures). Late payments of CIS/PAYE/NIC also attract 5% penalties at 30 days, 6 months and 12 months—plus interest. GPS can be withdrawn following HMRC review, but you generally have 30 days to appeal and, if accepted, GPS can continue during the appeal. GOV.UK
What penalties apply (and when)
A) Late CIS300 monthly return (filing)
File by the 19th following the tax month (6th→5th). Miss it and HMRC’s penalty timetable is:
- 1 day late: £100
- 2 months late: £200
- 6 months late: £300 or 5% of CIS deductions on the return (whichever is higher)
- 12 months late: £300 or 5% of CIS deductions (whichever is higher)
- Over 12 months: HMRC may charge up to £3,000 or 100% of CIS deductions (whichever is higher) for deliberate failures. Returns must not include negative values (use 0). GOV.UK
HMRC’s factsheet gives the same staging and explains when they’ll apply higher penalties for deliberate withholding. GOV.UK
B) Late payment of CIS deductions (to HMRC)
Pay by the 22nd each month if electronic (19th by post). Penalties on unpaid PAYE/CIS kick in at: 30 days (5%), 6 months (+5%), 12 months (+5%), on top of interest. GOV.UK+1
C) Wrong employment status declaration
On each CIS300 you declare subs are not employees. A wrong declaration can attract a penalty up to £3,000. If the engagement is employment, PAYE/NIC applies—not CIS. → See: CIS isn’t employment status: getting PAYE vs subcontractor right. GOV.UK
Appeals: how to challenge a CIS penalty (fast)
- Act within 30 days of the penalty notice—appeal online via your Government Gateway or write to HMRC quoting your UTR and the reference on the notice. You cannot appeal by phone. GOV.UK
- Reasonable excuse—HMRC can cancel penalties if a genuine, evidenced excuse meant you couldn’t file/pay on time and you put things right promptly after the issue ended (for example serious illness, bereavement). Reliance on someone else rarely counts unless you took reasonable care. GOV.UK
- Keep evidence—timeline, screenshots of HMRC service interruptions (if relevant), bank proofs, and your internal month-end checklist showing normal controls.
Tip: fix the underlying return/payment first so the appeal focuses purely on the cause and your prompt correction (HMRC note this positively in practice). GOV.UK
GPS at risk? How withdrawal and appeals actually work
- Scheduled review & CIS308: If you fail HMRC’s ongoing Tax Treatment Qualification Test (TTQT), they’ll issue CIS308 to withdraw GPS 90 days after the notice. If you don’t appeal by day 55, HMRC will warn your paying contractors (CIS316) that your treatment will switch to net from that 90-day point. GOV.UK
- Appeal window: You have 30 days to appeal the GPS withdrawal. If a late appeal is accepted, HMRC’s system reverses the switch (keeps or restores gross) and notifies contractors. GOV.UK
While appealing, GPS usually continues; if you ultimately lose, the switch to net will follow. Keep deductions and filings pristine during this period. GOV.UK
How to structure a strong appeal (penalty or GPS)
- Facts first: dates, what was due, when filed/paid, and by which method (with evidence).
- Cause: concise explanation, mapped to HMRC’s reasonable excuse language where relevant. GOV.UK
- Correction: proof that the return is now filed and/or payment made, with references.
- Controls (what’s changed): show the concrete fix (e.g., locked deadlines in software, dual sign-off, automated reminders), so HMRC sees future-risk is reduced.
Worked scenarios (to calibrate your response)
A) CIS300 filed 3 days late; first time
Appeal with evidence of unexpected outage/illness and same-day filing once resolved. HMRC guidance allows cancellation where a reasonable excuse existed and you acted promptly. GOV.UK+1
B) Paid CIS 40 days late
Expect a 5% late-payment penalty plus interest. Pay immediately, then ask for Time to Pay if cash-flow remains tight. Penalties escalate again at 6 and 12 months. GOV.UK
C) GPS withdrawal notice (CIS308)
File an appeal within 30 days. Provide a month-by-month table of filings/payments versus deadlines. If within HMRC’s published tolerance and/or with credible reasonable excuse, ask to maintain GPS. (Background on tolerance and timing in our GPS pieces.) GOV.UK
Controls that prevent penalties (and help keep GPS)
- Status first: decide PAYE vs self-employed with CEST and keep the output in the job file; only then consider CIS. → CIS isn’t employment status.
- Verify before first payment (and re-verify if the sub hasn’t appeared on your returns in the current or previous 2 tax years). → Subcontractor verification. GOV.UK
- Invoice split is non-negotiable: CIS on labour only; materials/eligible plant excluded from the base. → CIS invoice anatomy: labour vs materials.
- DRC done right (when in scope): no VAT on the invoice; customer reverse-charges on the whole supply, unless they’ve notified in writing they’re an end user/intermediary supplier. Keep that letter. → CIS vs VAT Domestic Reverse Charge. GOV.UK
- Month-end rhythm: issue Payment & Deduction Statements by the 19th, file CIS300 by the 19th, pay by the 22nd (electronic). → CIS300 & Payment/Deduction Statements. GOV.UK
- Software discipline: use your Xero/QuickBooks/Sage CIS codes, lock templates, and reconcile PDS ↔ CIS300 ↔ HMRC payment each month. → CIS returns & statements in Xero/QuickBooks/Sage
FAQ (practical & defendable)
How long do I have to appeal a CIS penalty?
30 days from the date on the penalty notice. Appeal online or by post; phone appeals aren’t accepted. GOV.UK
Can HMRC cancel a penalty?
Yes—if you show a reasonable excuse and you corrected the failure without undue delay. HMRC lists examples and what usually doesn’t qualify. GOV.UK
What happens if I don’t pay CIS/PAYE on time?
HMRC add 5% penalties at 30 days, 6 months, and 12 months late—plus interest. GOV.UK
If HMRC withdraws my GPS, can I keep trading gross during appeal?
If your appeal is lodged in time (or a late appeal is accepted), HMRC’s system keeps or restores gross and notifies your contractors accordingly. GOV.UK
Quick GOV.UK reference
- CIS300: deadlines, no negative values, penalty table & appeals. GOV.UK
- CIS late filing penalties (factsheet)—including higher penalties for deliberate failures. GOV.UK
- Pay CIS deductions to HMRC: due by 22nd (electronic). GOV.UK
- PAYE/NIC late-payment penalties (5% at 30 days/6 months/12 months). GOV.UK
- GPS withdrawal & appeals: CIS308, day-55 notifications, reversals on accepted appeals. GOV.UK+1
- DRC end-user/intermediary wording (written notification). GOV.UK