Hi Leah,
For Social Security of April must submit within 15 May 2016 as statutory.
After that, It’s penalty to payment.
It's calculated to 1500 * 2% Per month. I will submit to social security office on 28 June 2016 as usual for payroll of June
16 May – 15 June 2016 (1 month)= 30 Baht
16 – 28 June 2016 (13 Days)= 13 Baht (1500*2%*13/30)
Conclusion : If The day of submitting not change to 28 June 2016.
Client must payment on a cheque = 1,500+43 = 1,543 Baht.