The Salvation Army is paying $600,000 a year in tip fees to dispose of rubbish left outside its 125 family stores nationwide.
Workers at shops in the Wellington region said the problem was worse as Christmas approached.
Salvation Army lower North Island family store manager Gareth Marshall said dealing with unwanted "donations" left outside the 26 stores under his control was a "frustrating, significant issue for store staff".
He said the $600,000 paid in tip fees was money the army would prefer to give to needy families. "People who abuse us will abuse us, no matter what. We are still very grateful for everything we get," he said.
Stores were open six days a week with signs on doors asking people not to leave goods when the shops were closed.
There was also a significant pilfering problem. By the time staff arrived for work, particularly on Monday mornings, their first job involved cleaning up large piles of rubbish picked through by overnight pilferers.
"Staff become very frustrated when unwanted rubbish is left outside shops overnight and at weekends," Mr Marshall said.
The army's stores make about $10 million a year from selling used goods such as furniture, toys and books.
John Rossbotham, manager of the Catholic Church's six St Vincent de Paul shops in Wellington, said loading up a van to go to the tip on Monday mornings was part of the "cost of doing business".
"Vinnies" shops in Newtown, Miramar, Island Bay, Aro St, Johnsonville and Khandallah rarely had "donations" of household rubbish outside trading hours. Fairfax NZ
- Taranaki Daily News
Will Aaron Cruden's omission hurt or help the All Blacks?Related story: Senior All Blacks 'pretty disappointed' in Cruden