If this is your first payout, then your income tax for next year will increase quite significantly. I calculated that mine will jump by about 3k.

You can consider CPF top up or SRS contributions. However, you only get a one-off tax relief, and in exchange, your money is tied up in those accounts for the foreseeable future.

If you already savvy enough to invest your money in stocks/bonds, I wouldn't recommend doing either as it will tie your money up when perhaps it could have grown more investing them yourself. If you're not already actively investing, perhaps you can consider both options (CPF is a safe 4% return, SRS you have to do a bit more homework yourself). I will probably only consider contributing to CPF/SRS when my marginal income bracket hits 15% (if it ever does).