The accounts, held by Clemmow Hornby Inge and Initiative, cover Best, Reveal and the recent launch, Real People.
ACP-NatMag is drawing up a media shortlist, with pitches expected in the next month. It is expected to open talks with creative agencies shortly.
The move follows Andrew Kirkland's arrival in December as the group publishing director.
Last year, the publisher spent £5 million on media to support Reveal and less than £1 million on Best. It has a £6 million marketing budget for Real People.
CHI created Real People's launch advertising campaign, which featured the endline: "There's a time and a place to share your story."
This week, Vicky Mayer, the Real People editor, resigned. Louise Court, the editorial director of ACP-NatMag, will have editorial responsibility while a replacement is found.
ACP-NatMag, a joint venture between The National Magazine Company and Australian Consolidated Press, launched in 2004 and has experienced success with the circulation of Reveal, which also launched in 2004. The title's sales rose 44 per cent year on year to 345,502 for the six months to January. Best's sales were down 2.5 per cent to 400,807.