Originally Posted by Unregistered

Basic pay is what stated in your contract. (Before CPF deduction).

Gross pay is everything added in. (Include all bonus, AWS, overtime, allowance, etc)
Adding in employer's CPF contribution is subjective and most people don't factor this in gross, however, you can do so.

In fact, you can use tax assessment total income / 12. Employer's CPF contribution is not factor in.

HR will normally use 14, 15 or 16 months forumula to estimate gross pay.