Hiring external advisors is expensive!
How do you benefit from the knowledge and skills of specialists and still control the costs? External consultants are there for a specific purpose, for example to replace sick employees, for their unique skills  etc. External advisors are more expensive than internal employees, so it is important to hire them quickly but also to timely get rid of them.

RULE 1 – Talk to the external advisor who is actually going to do the work.
Big, well-known firms have partners that do the initial assessment, but they are not the ones doing the actual work. You get a manager (plus two trainees…) that will manage your case. Another alternative is a small specialized agency with good references. You speak directly to the people with knowledge and experience that will actually do the job. Check their references and negotiate the fee. The first cost benefit is already there: you don’t pay for the overhead or the corporate marketing.

RULE 2 – Agree in advance what will be done and how it will be reported.
Formulate the assignment clearly internally before hiring. Your employees will also know what the assignment is. This way, the interim manager/advisor/consultant also gets cooperation that he or she can really use for the successful implementation of the assignment.
The organization is informed and this shortens the turnaround time and increases the chance of success.
The reporting (delivery) moment must be clear and established in advance for everyone: be critical and give the advisor the opportunity to perform.

RULE 3 – Be in regular contact.
Maintain formal contact in order to make timely adjustments. Appoint a ‘supervisor’ from another department. Some outsiders like to work on several projects in different firms, but this makes it hard to control the working hours. Always know what they are doing! You can negotiate as hard as you like about the hourly rate, but a few extra hours will make an advisor with a low hourly rate quite expensive.

RULE 4 – Get rid of them in a timely manner.
Some agencies are masters at extending an assignment. Good agreements in the beginning (see above) will enable you to prevent this. Even if the process is delayed, there must be the flexibility to let the external employee go. As soon as the organization can continue under its own management, the advisor has to hand over and move on to the next project.
If their performed work is good, you can give a positive reference.

Note: When hiring the same person for a longer period (or multiple times), the Wet DBA * Act applies.

* The DBA Act (Deregulering Beoordeling Arbeidsrelaties) replaces the VAR (Declaration of Employment Relationship) since 2016. The DBA law is there to give the self-employed (ZZP-ers) and clients clarity on the employment relationship that is entered into. Unfortunately, the DBA Act has not brought the clarity that was expected. The law is and will remain in force, but will not be fully enforced until 1 October 2021. Meanwhile, new regulations are being drafted.