Section 6 (3) of RTI Act 2005 reads as follows :
Where an application is made to a public authority requesting for an information—
(i) which is held by another public authority; or
(ii) the subject matter of which is more closely connected with the functions of another public authority, the public authority, to which such application is made, shall transfer the application or such part of it as may be appropriate to that other public authority and inform the applicant immediately about such transfer: Provided that the transfer of an application pursuant to this sub‑section shall be made as soon as practicable but in no case later than five days from the date of receipt of the application.
To sum up, Section 6 (3) lays down provision where RTI application is received by a Public Information (PIO) and the information pertains to another PIO / Department, the application or any part of the application shall be transferred to the appropriate authority by the PIO.