I have read in The Majlis that it is not permissible to work under kuffaar.

Answer

Regarding the issue of working for a kaafir, we do not labour on this mas'alah, because the vast majority of the Ummah works for kuffaar. Their Imaan is of such a shaky and weak level that it would be futile to emphasize this mas'alah. Nevertheless sometimes we mention it in passing so that Ilm is not concealed.

While it is not permissible to work for a kaafir, the earnings will be halaal if the work is halaal.