Packed the picnic blanket? What about the dips and cheese? And don't forget the sunscreen and permit.

Permit? As Melburnians flock to parks and gardens for Australia Day and other celebrations this summer to soak up the sun and spend time with family and friends, some councils are charging for social gatherings with anywhere between 20 and 500 guests.

Mary Cantsilieris, right, who had about 20 people attend her birthday party, had no idea she may be required to buy a permit. Credit:Justin McManus

At some of Melbourne's most popular spots for a scenic afternoon, councils require groups to register and pay for a permit, which is then checked by patrolling council officers.

In Port Phillip, which includes popular bayside suburbs such as St Kilda, Elwood and Albert Park, parties of 20 or more people need an $82 permit, which buys them two hours to enjoy a beer and throw the frisbee around. Each additional hour costs $41.