Convert office to ROHQ (Manila)

Hi,

This may be a little bit out there, but googling it has not brought up anything, so I am wondering if anyone here knows the answer to this.

My employer started up their office in Manila quite small, so at that point just started it as an Inc. However, now that the office is expanding, it is quickly becoming the de-facto ROHQ, so we would also like to take advantage of the tax incentives the official status would offer.

So my question is, if it is possible to "declare" an ROHQ after the office has already been established and been operating for over a year. What I found online was only relevant to newly established subsidiaries.

Cheers

Christoph