To calculate the net first month's interest when the bank offers compound monthly interest, we need the following formula for compound interest:

$A = P \left(1 + \frac{r}{n}\right)^{nt}$

Where:

• $A$ is the amount after interest.
• $P$ is the principal amount (initial deposit).
• $r$ is the annual interest rate (in decimal).
• $n$ is the number of times interest is compounded per year.
• $t$ is the time the money is invested or borrowed for, in years.

To find the first month's interest, we will calculate the difference between the amount after 1 month and the initial principal:

$\text{First month interest} = A - P$

Assuming:

• $P$ is the principal amount.
• $r$ is the annual interest rate.
• $n = 12$ (since interest is compounded monthly).
• $t = \frac{1}{12}$ years (since we are calculating for one month).

Please provide the principal amount $P$ and the annual interest rate $r$, so I can complete the calculation.