Body leasing and a Werkvertrag get quoted against each other as if they were two prices for the same engineer. They are not. One gives you the right to direct the work day by day; the other buys a defined result and hands the direction right to the supplier. For AI and data work, where the specification changes in week two once someone has actually read your tables, the direction right is the thing you need, and body leasing is usually the cheaper contract even at a higher hourly rate.
What body leasing is, in contract terms
Body leasing is the market word for Arbeitnehmerüberlassung: a supplier lends you its employee, and you direct that person as if they sat in your reporting line. In Germany the supplier needs an AÜG licence to do it, and the consequences of operating without one fall on both sides, including the risk that the engineer is deemed your employee.
Three constraints come with the model:
- A maximum assignment of 18 months for the same engineer at the same client, unless a sector collective agreement extends it.
- Equal-pay obligations that bite after nine months, again subject to collective-agreement deviations.
- Documentation duties. The contract has to name the arrangement as Arbeitnehmerüberlassung and identify the engineer before the assignment starts.
Outside Germany the term is used loosely. In Poland and Romania it usually describes a business-to-business service contract with named engineers and no equivalent licensing regime, which is why a Warsaw supplier and a Munich buyer can use the same word and mean different obligations.
Werkvertrag: you buy a result and give up control
Under a Werkvertrag the supplier owes a defined work product, carries the risk of getting there, and accepts warranty obligations after acceptance. You cannot instruct the engineers. If you do it anyway, through daily stand-ups, ticket assignment and sprint direction, the arrangement can be reclassified as verdeckte Arbeitnehmerüberlassung, and a missing licence then becomes an expensive finding rather than a paperwork slip.
| Body leasing | Werkvertrag | Freelancer, contracted direct | |
|---|---|---|---|
| Directs the daily work | You | The supplier | Disputed in practice |
| Carries delivery risk | You | The supplier | You |
| Licence required in Germany | Yes | No | No |
| Duration limit | 18 months per engineer | None | None |
| Typical failure | The cap forces a handover | Change requests eat the saving | Scheinselbständigkeit finding |
What the choice does to the price
A Werkvertrag prices the supplier’s risk of being wrong about scope. On AI and data scopes, where discovery routinely moves the estimate by 40% or more, that premium sits somewhere around 20% to 35% above the equivalent time-and-materials rate, and it buys less certainty than it appears to, because every scope change reopens the commercial conversation.
Body leasing prices one thing: the engineer. Current figures per seniority sit on our daily rates page, and the arithmetic against a permanent hire is worked through in our note on how a recruitment fee compares with rented capacity.
Which shape fits which work
Use a Werkvertrag when the deliverable can be written down and tested by someone who is not in the room: a schema migration with a reconciliation report, a defined integration, a decommissioning. Use body leasing, or its time-and-materials equivalent in IT staff augmentation, when you are building a retrieval pipeline, tuning a model, hardening an agent, or doing anything where you will change your mind about the target once you see the first evaluation numbers.
The signal is simple. If you would be uncomfortable letting someone else decide the sprint order, you need the direction right, and only one of these contracts gives it to you.
Where body leasing is the wrong answer
Three cases. If you have no engineering manager with capacity to direct the work, rented engineers will drift, and a dedicated team with its own lead is the better shape. If the role is permanent and central, the 18-month cap makes body leasing a bridge rather than a destination; hire, and rent only until the hire starts. And if you genuinely need a fixed date with penalties attached, accept the Werkvertrag premium rather than pretending a time-and-materials contract carries that risk. It does not, whatever the slide says.
If you are unsure which side of the line your work falls on, the definitions and contract mechanics are set out separately.