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The question often comes up after a disappointment: an agency whose results nobody can see, or a new hire left alone facing ten different jobs. People then look for the right formula, as if there were one. In reality, an agency and an in-house team do not do the same work, and both have their place in a company of 20 to 500 people.
This article offers an honest calculation, without bias towards either, even though we are an agency ourselves. It complements our guide to marketing automation for SMEs and our article on the marketing budget, where people are often the largest line.
In short
Compare full costs for the same volume of work, not a salary with an agency invoice.
The in-house team knows the trade, reacts fast and keeps the memory; the agency brings specialist skills, an outside view and capacity for peaks.
The most common model is mixed: the in-house team steers and owns the accounts, the agency carries out specific projects.
AI lowers production costs on both sides; judgement, review and strategy stay with people.
What companies that brought work in-house do
The US Association of National Advertisers (ANA) measures every five years the share of its members that have built an in-house team for work once given to an agency. Its 2023 figures mainly show that in-housing does not replace agencies:
of members surveyed have an in-house team doing agency work
still work with external agencies
have brought in-house some work previously handled by an agency over the past three years
According to the same study, work goes to an agency mainly for two reasons: the in-house team is already full, or the agency has a skill that does not exist in-house. These figures come from large American companies; they show a trend, not a norm for an 80-person company.
What each option really costs
Comparing an annual salary with an agency invoice skews the calculation both ways. Each option has costs the other does not.
In-house team
Salaries and employer costs, for each skill needed
Recruitment, onboarding, ongoing training
Tools and licences in the company’s name
Management time, and continuity to organise (holidays, departures)
Agency
Fees, fixed, time-based or results-based
In-house time to brief, approve and review
Switching cost if the relationship ends
Dependency if the agency holds the accounts or the data
The calculation, in four steps
- List the work.
Recurring tasks and their monthly volume: campaigns, content, advertising, reporting, website. Without this list, you are comparing intentions.
- Cost the in-house option.
The full cost of the people needed for that volume, including tools, management and recruitment time.
- Cost the agency option.
Fees for the same volume, plus the time your team will spend briefing, approving and reviewing.
- Compare at equal skill.
One person rarely covers advertising, content, SEO and tools at the same level; an agency rarely covers your trade as well as you do.
Step four is the one people forget. A single versatile hire may cost less than an agency, but does not replace a paid search or technical SEO specialist. Conversely, an agency that quickly produces generic content is expensive if every text has to be rewritten by an in-house expert.
What the in-house team does better
- Knowing the trade. It speaks like your customers, knows what is true and what is not, and produces the expert content that convinces: customer case studies, webinars, short videos featuring the team.
- Working with sales. The rule for handing a contact to sales is easier to settle between colleagues than through a contract.
- Keeping the memory. What worked, what failed, and why: the history stays in the company.
- Reacting fast. News, a customer question, a correction: decision and execution sit in the same corridor.
What the agency brings
- Specialist skills, at the right time. Setting up an ad account, auditing a website, putting in place reporting that ties spending to sales or attribution that says which channel sold: projects you do not run every month.
- An outside view. It sees other companies, other markets, other mistakes, and can say what the team no longer dares to notice.
- Capacity for peaks. A launch, a trade show, opening a country, as our international SEO guide describes.
- Watching the tools. It tests what changes in the platforms for several clients at once.
For advertising, what an agency mandate should contain (access, reports, account ownership) is detailed in our article on the Google Ads agency contract; its rules apply to other services too.
The mixed model, the most common
In most companies of this size, the split that lasts looks like this: one or two people in-house steer the marketing plan, handle the relationship with sales and produce the expert content; an agency or freelancers take on the specialist projects and the peaks.
Watch out
What stays in the company’s name
Ad accounts, the CRM, the email sending tool, the website and its access must be in your company’s name, whatever the provider. An agency works on them with delegated access. The day the relationship ends, nothing should leave with it.
This split requires shared tools: a CRM where every contact keeps its source, campaigns sent following a written method, from a domain whose deliverability is checked, a newsletter and segmentation everyone can read. As for distribution, the choice between the company page and the leader’s profile on LinkedIn cannot be fully delegated: the leader’s voice remains their own.
What AI changes in the calculation
AI cuts production time on both sides: first drafts, variations, transcriptions, content offered in exchange for an email address formatted faster. It removes neither trade expertise nor review: generated text must always be reviewed, sourced and signed. The calculation therefore shifts: a small, well-equipped in-house team produces more than before, and an agency is worth most for what the tool does not do, judgement, method, measurement. This shift is covered in AI and digital marketing: what changes for agencies.
From the field
Agents that produce, a person who publishes
Our own content engine has worked this way since August 2026: four AI agents analyse search data every day and prepare drafts, and nothing is published without a person’s review and decision. The tool changed the possible volume; it did not change who answers for what goes out.
Where to start
List the marketing work of the past twelve months, with the time actually spent and who did it. Identify what requires knowledge of the trade (to keep in-house) and what requires a specialist or occasional skill (to outsource). Then check that every account and every tool is in the company’s name. If you want to outsource the technical projects while keeping control, our digital marketing offer works on your accounts and your CRM, never on ours.
Frequently asked questions
At what size do you need an in-house marketing team?
There is no universal threshold. As soon as marketing needs continuous follow-up (regular content, campaigns, the relationship with sales), at least one in-house person who steers becomes useful, even if they rely on contractors. Before that stage, a leader who keeps control and an agency for specific projects are often enough.
Is an agency more expensive than an employee?
It depends on the volume and the skills compared. An agency charges more per hour, but you only pay for the work ordered, with several specialities behind it. An employee costs less per hour, but full time, with recruitment, tools and management. The fair calculation compares full costs for the same work at the same skill level.
How do you avoid depending on your agency?
Keep the ad accounts, the CRM, the website, the email tool and their access in the company’s name, and give the agency delegated access. Ask for regular reports in a format you can read without it, and documentation of what is in place. The day you change provider, everything stays with you.
Does AI let you do without an agency or a team?
No. It cuts production time for text, visuals and analysis, but someone has to decide what to produce, check what is true, review and answer for what goes out. It changes the team size needed and the nature of the work given to an agency, without making either one useless.
Jim · founder of Brain Plus AI
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