To send money from Mpesa to Mwalimu Sacco FOSA account, Go to Safaricom then Mpesa, select Lipa na Mpesa, select Paybill, and enter Mwalimu Sacco Paybill number 541900 as Business number, enter your National ID number as account number, enter the amount you want to send, enter Mpesa pin and complete the transaction.
FOSA paybill number is used for depositing to shares or saving accounts that can be withdrawn over the counter.