You’ve probably heard you can’t use the same subby for more than 13 weeks. Or was it six months? A year? Maybe someone told you 24 months is the magic number, or that you need to give them a break to “reset the clock”.
Here’s the truth: there is no legal time limit on how long you can work with the same subcontractor.
None. Not 13 weeks, not six months, not a year. You can work with the same subby for months, years, even decades, if the relationship is genuinely self-employed.
But – and it’s a big but – there’s a catch. Let’s look at what actually matters.
The Myth of Time Limits
These myths don’t come from nowhere. Some payroll companies repeat them to scare contractors into using umbrella solutions. Contractors repeat them to each other. And IR35 rules get misunderstood and turned into made-up deadlines.
The law itself is clear. There is no statute, regulation or HMRC guidance that sets a maximum length for subcontracting relationships. HMRC’s own Employment Status Manual explicitly recognises that long-term engagements can still be genuine self-employment, and even gives examples of long-standing arrangements that remain compliant.
The confusion often comes from agency worker regulations, which don’t apply to construction subcontractors. Or from outdated ideas that self-employed workers must constantly rotate between clients. That simply isn’t true.
What HMRC Actually Looks At
HMRC doesn’t care how long you work with someone. They care how you work with them.
Employment status is assessed using well-established tests, including:
- Control: who decides what work is done, when, where and how
- Mutuality of obligation: is there an expectation of ongoing work and acceptance
- Personal service: can the individual send a substitute
- In business on their own account: do they have multiple clients, equipment and financial risk
Length of time alone isn’t decisive. Although it may cause HMRC to take a closer look.
Why Long-Term Relationships Attract Scrutiny
If the same subcontractors appear on your CIS returns month after month, HMRC will notice. They are currently reviewing patterns across 12 months of CIS data, particularly where the same names recur.
That doesn’t automatically mean employment, but it does increase scrutiny.
Regular work combined with consistent acceptance can suggest mutuality of obligation. If you offer work every week and the subby accepts every week for years, HMRC may argue that the relationship looks more like employment than a series of independent contracts.
However, HMRC’s own guidance makes clear that long tenure can be outweighed by other factors. Multiple clients, genuine substitution, significant equipment, and real financial risk can all suggest genuine self-employment. Even over many years.
Problems arise when long-term relationships quietly drift into employment-like arrangements. Guaranteed work. Exclusivity. Control over methods, not just outcomes. Company tools, uniforms, vans, start times identical to employees. That’s when time becomes an issue.
How to Work Safely With Subbies Long-Term
Working with subbies long-term isn’t illegal or even risky if you do it properly.
Document the reality.
You need contracts that reflect how you actually work together, not idealised templates. HMRC compares contracts to operational reality. If your paperwork says one thing and your site practices say another, that gap becomes potential evidence against you.
Avoid employment characteristics.
Don’t guarantee work. Don’t require acceptance. Don’t dictate methods. Don’t provide holiday pay, sick pay or employee benefits. Treat subbies as independent businesses, not informal staff.
Be careful with social media too. Photos of your “team” in matching uniforms described as staff can directly undermine your self-employed position. HMRC does look.
Review arrangements regularly.
Relationships evolve. Annual reviews help ensure contracts still match reality. Artificial breaks don’t help as HMRC will see straight through attempts to “reset the clock” with token gaps.
The Bottom Line
You can work with the same subbies for as long as the work requires. Time isn’t the issue. The working relationship is.
Focus on genuine self-employment: autonomy, substitution, financial risk, multiple clients and proper documentation. Get that right and long-term relationships are not only acceptable, they’re sensible.
Want to work with subbies long-term without the compliance risk? HardHats’ insurance-backed contracts are designed to document genuine self-employment and protect you if HMRC ever challenges your arrangements. Get in touch to find out how we can help.