He vowed to do Hajj every year but his boss at work will not let him do that

Praise be to Allah.

If what is preventing you from doing Hajj in some years is something that is beyond you control and you cannot do anything about it, then there is no sin on you, because Allah says (interpretation of the meaning): “Allaah burdens not a person beyond his scope” [al-Baqarah 2:286] and “Allaah does not want to place you in difficulty” [al-Maa’idah 5:6]. 

And Allah is the source of strength; may Allah send blessings and peace upon our Prophet Muhammad and his family and Companions. End quote. 

Standing Committee for Academic Research and Issuing Fatwas. 

Shaykh ‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz, Shaykh ‘Abd al-Razzaaq ‘Afeefi, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn Qa’ood