Can someone please help me with this journal entry:

Borrowed $15,000 from the bank by issuing a 12-month note. Interest accrues on the note at the rate of 12% annually, or 1% per month. Interest is to be paid when the note is due next year.

When receiving cash:
Dr. Cash 15,000
Cr. Notes payable 15,000

Each month to record the interest expense:
Dr. Interest expense 150
Cr. Interest payable 150

When paying back the note:
Dr. Notes payable 15000
Dr. Interest payable 1800
Cr. Cash 16800

I agree with Kong.

Unless you are preparing monthly financial statements, no need to calculate the interest every month though, just when it is time for payment or a financial statement is being released.