LAST year, I wrote to the Straits Times Forum after I did not receive my Workfare Income Supplement payment despite having made the required Medisave contribution, as determined by the Inland Revenue Authority of Singapore (Iras) ("System glitch in Workfare payment"; Forum Online, Nov 17, 2014).

The Central Provident Fund Board replied ("Medisave contributions for Workfare: CPF Board replies"; Forum Online, Nov 22, 2014) and also called me.

I had previously overpaid my required Medisave contribution and used the extra amount to offset my current liability. This meant that I would have to contribute less to Medisave this time.

However, the CPF Board explained that I could not do this if I wanted to qualify for Workfare, as its system treated my smaller payment as only a partial payment.

I ended up having to pay the rest of the sum, which amounts to an overpayment.

Even though this problem was brought to the attention of the CPF Board and Iras, the same problem has surfaced again this year.

Again, Iras used the overpayment to offset the amount of my Medisave liability this year. The CPF Board's Notice of Computation instructed me to pay what Iras has determined to be my net outstanding Medisave payable.

This gives me the impression that Iras' and the CPF Board's computer systems are not in sync, even though it is expected to be so for these matters.

I hope the confusion can be eradicated once and for all.

My voluntary Medisave contributions should be treated as compliance on my part, and not as overpayment, and used yearly to compute my liability.

Seah Kian Chong