The league is also satisfied that the Barclays Premier League champions have not broken any rules over their signing of the former England midfielder.
Lampard, 36, was expected to join City's sister club New York City full-time this month having apparently been on loan in Manchester from the American outfit.
But now it seems that Lampard, despite being announced as a New York signing last summer, has never signed any formal contract with the Major League Soccer newcomers.
Lampard had actually been on a short-term, full-time deal with City for the first half of the season and that was extended to the end of the campaign on New Year's Eve.
It means confusion remains over what exactly Lampard had agreed with NYCFC, who had publicly announced they expected the player to join up with them on January 1, while Lampard also fronted their season ticket marketing campaign.
There have been suggestions that Lampard might actually have signed with the City Football Group - the parent company for both clubs - but the Premier League has indicated there is no provision for a move to NYCFC.
The league has looked into the matter, feeling it needed to ascertain who owned Lampard's contract to safeguard the integrity of its competition.
And, despite the confusion, it has concluded nothing untoward has occurred.
A Premier League statement read: "Frank Lampard is registered with Manchester City FC until the end of the 2014-15 season.
"The Premier League has sought and received assurances from Manchester City that there is no agreement in place between the club or City Football Group with New York City FC relating to the player."
City have not yet responded to requests to clarify the situation.
New York City said on December 31 they were unsure when Lampard would now join them.
"His exact starting date with New York City FC will be confirmed as the EPL and MLS seasons unfold," a statement read.
Lampard, released by Chelsea at the end of last season, has made a positive impression at the Etihad Stadium and scored seven goals so far this term.
Source : PA
Source: PA