For a very limited period, Big Finish is pleased to invite prospective writers to pitch ideas for a one-off, 25-minute Fifth Doctor and Nyssa audio adventure, which we hope will make up one of four single-episode stories comprising a future Doctor Who release.
Brief details can be found here and the full PDF is here.
I can't find any mention of payment, but this is a little more about the company.
For nearly ten years Big Finish has been producing high-quality science-fiction audio drama on CD. There are literally hundreds of productions to choose from, with new titles being released on a monthly basis. The majority of Big Finish's audio plays are based on popular TV series such as Doctor Who, Dark Shadows, and Sapphire and Steel. Many of the original actors who starred in these classic shows have returned to recreate their characters. Each release is a full-cast audio drama with explosive sound design and an original music score. Every story features your favorite characters in an all-new adventure. Big Finish offers hours of entertainment, excitement and intrigue. You've never heard it so good!
Apologies for short notice, the deadline is Monday 1 February, but I've only just become aware of this.