Visa question of the month - Valid visa in expired passport?

My B-1 Visa which is valid for another 3 years, is in my passport, which has now expired. I had applied for the visa for my former employer, where I am no longer employed.
How can I have the visa transferred to the new passport? And can I still use the visa for assembly work in the USA for my current employer?

There are two pieces of good news for you here:

Although it is not possible to transfer a still valid US Visas from an expired to a new passport by the US authoritiesyou can still use the visa. Thus, the validity of the visa is not linked to the validity of the passport it is in.
In practice, this means for you: In the future, when entering the US, you would first have to show your new (still valid) passport and additionally the old (expired) passport including your still valid US visa.

However, the prerequisite is that your master data has not changed in the meantime. I.e. your name, gender and nationality must match in both passports.
For example, if you are a dual national with German and Italian nationality, and you have the B-1/B-2 visa in your German (expired) passport, you cannot use your Italian passport in combination for entry. If your name has changed in the meantime due to marriage or divorce, we generally advise rather to apply for a new visa in order to avoid problems at the border. In case of very urgent travels, people can also try to explain the name change at the border by means of a marriage or divorce certificate. However, it is then up to the officials to decide whether or not to allow you to enter the country.

However, if nothing has changed in your master data from the old to the new passport, you can therefore travel as usual (but then with both passports). You do not need to apply for a new visa.

As a Tip: When reapplying for or canceling your old passport, be sure to inform the passport authorities that the passport still contains a valid visa. If the visa is damaged due to a puncture, for example, it can no longer be used and you will have to apply for a new visa.

Furthermore, the B-1 visa is personal and not employer-bound, as it is a business visa. This means that you can continue to use this visa for e.g. business meetings, contract negotiations or even certain assembly activities for your new employer.