Almost every foreigner who enters the Philippines will get a visa for 21 days. Read about the latest updates if you are also entitled. If you are planning to stay longer you have to go to one of the many Immigration Offices in the country and apply for an extension. Your first extension will be 38 days. After that you are able to have more extensions for 2 months each time you apply.
There are rumors that this can only be done until you are 16 months in the Philippines. But my experience is that even after 16 months there is still the possibility to have more extensions. If every Immigration Office knows these rules, I do not know. In those cases you better go to one of the bigger offices which usually can be found in Province capitals.
(links to government sites in the Philippines are often broken, why? They have more traffic than the hosting company allows !!)

The above is only if you are in the Philippines on a Tourist Visa. In cases that you came here and got the Balikabyan status first for 1 year, and after that got the tourist visa, this tourist visa starts on the date after your Balikabayan status has expired. So, it is possible to stay in the Philippines for much longer than 2 years and 4 months.

the written BB is your balikbayan status

Balikbayan status is granted to spouses (and children) of Philippine citizens or born Filipino’s. This status stamp will be given to you when you enter the Philippines, together with your spouse, upon arrival at the immigration booth at the airport. If not given automaticaly, you better ask for it.

Flor and I entered the Philippines October 5, 2008. After the balikbayan status expired, I applied for the tourist visa which was easy. My first tourist visa was for two months. Every two months we went to the Immigration Office in Intramuros to extend it, and every time it was no problem. The maximum extension is two months each time. take care that you do not overstay, because you have to pay extra fines.

Next time I will go to the Immigration office I will apply for a 13a visa. I will report about that later.

NOTE: the shown pictures are not those of my passport, I was lazy to make pictures myself, so I used them from collegue Expats in the Philippines. If you click on the pictures you will be directed to the respective websites of them.