The couple have been romantically linked since September, following the One Direction star's split from girlfriend Danielle Peazer.
The romance has yet to be officially confirmed by the pair, with Lewis firstly denying that they were an item. However, she later described Payne as a "really sweet" guy, saying that she finds it is "best not to talk" about her personal life.
Payne is said to be in New York in the lead-up to Christmas, while Lewis is in Hackney, London.
The pair have reportedly arranged a romantic trip to Los Angeles, California for a few days in December, according to The Sun.
A source said: "Leona and Liam only starting seeing each other recently.
"But because of work, they won't be together for a while now.
"They thought this was a nice thing to look forward to."
Liam Payne admitted last month that he "has a crush" on Leona Lewis, but did not confirm any relationship.