1) Should I buy SSBs using SRS funds instead of cash? 2) I'm a young working adult. My tax is abt $400/year. Should I be looking at contributing to SRS now, or use my cash elsewhere?

By contributing to SRS, the fund will be locked till 62 years old. And the tax saving for yr case is not justifiable to put yr money to SRS. U can consider SRS when yr tax bracket hit 11% or 15%.

Personally, paying $400/year for taxes would not be significant enough for me to want to contribute to SRS. For cash, short term funds park them into Savings Account, SSB, or Bonds and long term funds (5 years) into Stocks. Otherwise, topping up CPF for tax relief would still be of a higher priority for me than SRS contributions.​​​