Employment in a German company generally mandates full social contributions to be paid. For most employees it means they have to get on statutory/public insurance (comprehensive private insurance only an option for high earners - over €69300 yearly).
However, there are three types of of employment which actually do not always mandate full social contribution, or even German insurance:
Short-term employment
Seasonal employment
Here, we will focus on the short-term, and seasonal employment.
Short-term employment
This is the case when the activity is limited to a maximum of three months or 70 working days within a year, and the job is not performed on a professional basis. If the salary exceeds €538 per month, for short-term employment, it still applies that this employment does not constitute regular employment. Therefore, this type of employment is free of social contributions. One exception applies to the statutory accident insurance: according to this, people employed for a short period are insured against accidents by law, whereby the employer pays the accident insurance contribution.
People who are insured in EU/EEA, the UK, Switzerland, or another country Germany has a social agreement with, can stay on their home insurance and use EHIC/GHIC for access to healthcare here. People from any other country need to get short-term private health insurance, such as our expat health.
Seasonal employment
The Federal Government defines seasonal workers as “employees who are temporarily employed by an employer domiciled in Germany and carry out activities, which, due to a recurring seasonal event or a recurring sequence of seasonal events, are tied to a particular season, with the demand for labor significantly exceeding the demand for the activities normally carried out in:
agriculture and horticulture (e.g., harvest helpers on special crop farms specialising, for instance, in fruit growing, vegetable production or viticulture).
tourism, especially in hotels and restaurants and in businesses or parts of
businesses, which are not open all year round (e.g., beer gardens, ski huts) or which have to cover an increased demand for labor during certain limited periods (e.g., restaurants popular with day-trippers)
fairground industry (e.g., accompanying personnel for rides) (Zoll n. d.)
Seasonal employment is generally free of social contributions in Germany only if it is a short-term employment (see the rules above).
If seasonal employment exceeds those limits, full social contributions need to be paid in Germany, which means the employee will need to get statutory/public health insurance. Only people who are insured in the EU and are also working there might be exempted under certain conditions.
Since there are multiple factors that come into account, it's best to fill in this questionnaire designed by the official German job agency, and send it to your employer. They will then determine if you need German insurance, and which type exactly.