CPF housing grant eligibility will affect which and how much HDB grants you can get for BTO, resale flat and EC buyers. Here is an overview on the 3 types of CPF grants available and their eligibility criteria.
Certain BTO eligibility and resale flat criteria have to be fulfilled to buy an HDB flat in Singapore. For a 4-room, your household income cannot exceed $14,000 (or $21,000 if purchasing with extended or multi-generation family).