How Much Did I Earn Last Year + Witholding Tax and Why I'm not Filing For ITR this year

Here's my earnings as an ESL teacher for the period of January 2018 to December 2018: 

Php 294,370 

Tax withheld from my company:

Php 17, 356.40 


As for the Train Law, the tax that I would pay is only:

Php 3,549.6 

With calculations of: 

Php 294,370
-Php 250,000 (Train Law)
----------------------
Php 44,370 
- 8 percent
______________

Php 3, 549.6



Why I'm not filing for ITR this year? 


I registered as Self-employed at BIR this January and I don't want to go through the hassle of filing for late ITR since I didn't file for the quarterly tax and so on. I decided to fully take advantage of Train Law this year. I know, sayang ang tax refund coz they withheld Php 17k+, but that's okay... for the Philippines naman yun eh. Heheh. Can you hear the sarcasm there?