The Australian Education Union (AEU) is defending a decision to pay a private recruitment company $500 for each new union member.
Victorian secretary Brian Henderson says the union outsources recruitment through the company Work Partners, to boost numbers.
The Australian Workers Union (AWU) national Secretary, Paul Howes and other union officials have criticised the practice.
But Mr Henderson says AEU membership has increased by more than 5,000 and says it is completely justified.
“I don’t know why people are critical, because the ACTU wants us to grow union membership, and that’s exactly what we’re doing,” he said.
“We’ve done the cost of the economics of recruiting to us, and the lifespan of the member, and it represents extremely good value for money.”