Which forms you're supposed to file can be seen in your Certificate of Registration (COR).
Look for the relevant section (highlighted in purple below) in your COR:
Each Tax Type corresponds to the following forms:
"Percentage Tax - Monthly" OR "Percentage Tax - Quarterly"
2551Q (Quarterly)
Note that the BIR "phased out" the 2551M forms as part of the TRAIN Act
"Individual Income Tax"
1701Q for Q1, Q2, Q3
1701/1701A for the whole year
"Income Tax"
If you are an individual (sole prop or professional), this would be 1701Q and 1701/1701A (similar to above)
If you are registered as a corporation, this would be 1702Q and 1702
"Withholding Tax - Exp/Oth"
0619E (Monthly)
1601EQ (Quarterly)
"Value-Added Tax"
2550M (Monthly)
2550Q (Quarterly)
"Withholding Tax - Compensation"
1601C (Monthly)
1604CF (Annual)
In Taxumo, you indicate which Forms you are filing in the Company/Profile Screen. At the bottom there is a section that you need to update:
Simply select the boxes that correspond to the form/s you are supposed to file. Click on "Save Changes" and you're done!
If you want to see the deadlines for forms you can file through Taxumo, you can refer to this article: All about deadlines