Hi @MTLfreelancer, I ended up including the provincial sale tax (PST) in line 3A, together with the GST that I had collected. I found this was reasonable since the form T2125 takes 3A minus 3B to obtain cell 3C, and since 3B explicitly indicates that it should include PST (as far as I undertand, QST is one of the PST's).
This is how I submitted it, although I am not an accountant or a tax consultant so please do not consider this as a professional advice.
