The short answer
A senior in-house social lead in London on £50,000–£85,000 costs a UK employer roughly £58,000–£98,000 a year once employer National Insurance and minimum pension are added, plus a one-off recruitment fee. A fractional head of social costs a fixed monthly fee with no on-costs, and you can stop at the end of the term. An agency gives you production capacity, but your fee buys hours from a team, not one senior owner.
Which one is right depends on two questions: how much senior thinking your social needs each week, and how much content you need produced.
What does an in-house head of social cost in the UK?
Salary is only part of the cost. For a permanent hire, a UK employer also pays:
- Employer National Insurance: 15% on earnings above £5,000 a year in 2026/27.
- Workplace pension: a minimum employer contribution of 3% of qualifying earnings, which for 2026/27 are earnings between £6,240 and £50,270.
- Recruitment fees: agencies typically charge 15–20% of first-year salary for a permanent placement, and up to around 30% for hard-to-fill roles.
Morgan McKinley's 2026 London salary data puts social media managers with 5+ years' experience at £50,000–£85,000.
Worked example: a £70,000 hire
- Salary: £70,000
- Employer NI: 15% × (£70,000 − £5,000) = £9,750
- Minimum employer pension: 3% × (£50,270 − £6,240) = £1,321
- Annual employment cost: about £81,071, or about £6,756 a month
- Recruitment fee at 15–20%: £10,500–£14,000, paid once
This excludes equipment, software, training, benefits and the months it takes to recruit and onboard. If the role takes three months to fill, that is a quarter with no senior owner on social.
What does a fractional head of social cost?
A fractional head of social is a senior lead who runs your social strategy part-time, on a fixed retainer. You pay a monthly fee, with no NI, pension or recruitment fee, because they are not your employee.
At Studio SG, the Partnership is £4,500 a month on a 6-month term or £4,000 a month on a 12-month term, plus VAT. That covers our founder leading your account, a monthly review and quarterly plan, and delivery from a vetted specialist bench when you need it. If your business is VAT-registered, you can normally reclaim the VAT.
The trade-off: a fractional lead is not in your office five days a week. It works when you need senior direction and a plan your team can deliver, not someone to post every day.
What does a social media agency give you?
An agency is the right choice when the main need is volume: lots of content, across lots of channels, every week. Retainers vary too widely to quote a fair average, so ask every agency three questions before you sign:
- Who, by name, will run my account day to day, and how senior are they?
- How many hours a month does my fee buy, and from which roles?
- What is the notice period, and who owns the content and accounts if we leave?
Side-by-side comparison
- In-house hire: full-time focus and deep brand knowledge. About £81,000 a year for a £70,000 salary, plus recruitment. Slowest to start, hardest to unwind.
- Agency: production capacity and a wider team. Fee depends on hours and roles. Seniority on your account varies.
- Fractional head of social: senior strategy from week one on a fixed fee, with flexible delivery. Part-time by design.
Which option fits your stage?
- Choose fractional if social has no senior owner, you are spending money without a clear plan, or you want to test what the role needs before hiring.
- Choose an agency if your strategy is already clear and the gap is production volume.
- Hire in-house if social needs a senior decision-maker every day, and you can wait for the right person.
You can also use them in sequence: a fractional lead sets the strategy and writes the brief for the in-house role, then hands over.
Not sure where you stand? The Sprint is a 3-week, fixed-fee audit that ends with a 90-day plan, so you can decide with evidence.
Frequently asked questions
What is a fractional head of social?
A senior social media lead who works with your business part-time, on a retainer, to own strategy, planning and reporting. They are not an employee, so there is no National Insurance, pension or recruitment fee.
Is a fractional head of social cheaper than hiring?
Usually, for the same seniority. A £70,000 London hire costs about £81,000 a year with employer NI and minimum pension. A fractional lead at £4,000–£4,500 a month costs £48,000–£54,000 a year plus VAT, with no recruitment fee. The difference is that a fractional lead is part-time.
How long should a fractional engagement last?
Six months is a practical minimum to plan, run and measure a full quarter of activity. Twelve months suits brands that want a lead to own social for the year.
Can a fractional head of social manage our in-house team or agency?
Yes. A common setup is a fractional lead setting strategy and reviewing work, with an in-house coordinator or an agency producing content.