Spotify's unconventional plans to go public appear to be moving forward.

The music-streaming company has confidentially filed for a public listing, sources told CNBC. Spotify declined to comment.

In the past, sources have told CNBC that Spotify would put a direct listing on the NYSE sometime during the fourth quarter of 2017 or first quarter of 2018, assisted by Morgan Stanley, Goldman Sachs, and Allen & Co. On Wednesday, sources added that Spotify had been trying to confidentially file in the fourth quarter, as early as October, but still didn't have SEC clearance.

Once Spotify obtained that clearance, it was able to file an F-1, an SEC document for foreign private issuers that serves as a catchall for first-time security offerings.

Spotify, which was founded in Stockholm, initially thought that it may not need to do a quiet period or a traditional F-1. But as part of the SEC clearance process, it now needs both, sources said.

Axios previously reported some details, citing unnamed sources, including that Spotify filed IPO documents in December for a public offering, citing unnamed sources.

A direct listing is slightly different than a traditional IPO. During an IPO, the company offers investors shares first, which allows underwriters to set an initial price. A direct listing allows investors to buy shares only through the open market, with no predetermined price.

News of Spotify's F-1 filing comes on the heels of a new copyright lawsuit against the company. Wixen Music Publishing claims that Spotify used thousands of songs without a license.

But sources told CNBC that it is "business as usual" at Spotify, and the suit is not seen as overly concerning in terms of the public offering.

— Written by CNBC's Anita Balakrishnan. Sally Shin and Reuters contributed reporting.