The Commerce Commission will issue guidelines in November outlining the best practice for school uniform sales.
The issue has been in the spotlight after a uniform shop in Auckland was threatened with an injunction if it sold uniforms for its local college.
The Uniform Shoppe in Papakura says Rosehill College is trying to force it out of business to protect the school's own income from uniform sales.
However, the school says it is concerned about uniform quality.
The commission's director of competition, Deborah Battell, says new guidelines will provide guidance to schools about how to avoid breaching the Commerce Act when supplying school uniforms.
Ms Battell says schools must be transparent about how they select a tender for uniform supply, and arrangements also have to benefit parents.
The Uniform Shoppe says Rosehill College has threatened it with an injunction to stop selling its uniforms in an attempt to steer sales to its school shop.
Managing director Janet Igrisan says the college has also told garment manufacturers not to supply her company.
She says she has received two letters from the school's lawyer, both threatening legal action against her and her company.
In a letter to the board of trustees, Mrs Igrisan says she will keep serving Rosehill College customers.
College principal Graeme Macann says the school shop is the sole provider of uniforms because of a recent quality issue.
