A $900 annual bill is due in five months. Is $75 a month enough?

Dividing a $900 yearly bill by 12 gives a useful long-run budget of $75 per month. It does not tell you whether you will have enough for the next due date. In this example, the bill is due just after five month-end deposits, and $150 has already been set aside. We assume no interest and no change in the bill amount.

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Draw the boundary around this one bill

The $150 starting balance is money already assigned to this bill. It is not the full balance of a bank account that also pays rent or holds emergency savings. Counting the same money toward two goals makes both plans look easier than they really are. Keep the bill amount, allocated savings and number of remaining deposits explicit.

Calculate the catch-up amount

The gap is $900 − $150 = $750. With five deposits available, the requirement is $750 ÷ 5 = $150 per month. After the first deposit, the reserve is $300; after the third, $600; after the fifth, $900. These milestones make it easy to check the plan without an interest-rate assumption.

See why the annualized amount falls short

Five deposits of $75 add only $375. Add the existing $150 and the reserve reaches $525, leaving a $375 gap at the due date. The $75 figure is not mathematically wrong; it answers a different question: how much to set aside each month across a complete 12-month cycle starting from zero.

Count deposits, not calendar labels

The model assumes five deposits happen before the bill must be paid. If the bill is due before the fifth deposit clears, only four deposits are available. The same $750 gap then needs $187.50 per deposit. Choose the number based on your actual planned transfer dates and payment deadline; the tool does not inspect a calendar or your bank’s posting times.

Reset the plan after payment

If the reserve reaches $900 and the bill consumes all $900, it returns to zero. For an unchanged bill 12 months later, twelve $75 deposits will refill it. Do not carry the previous $150 or the already-spent $900 into the next calculation. A new cycle starts with what remains after the payment, not the previous peak balance.

Allow the bill amount to change explicitly

A future renewal may be different. To explore a $990 bill across a fresh 12-month cycle, use a $990 target, zero starting balance and 12 months at 0%. The result is $82.50 a month. This is an input change, not a prediction that the provider will raise its price. Confirm the actual renewal amount when available.

Reproduce the first-year plan

Load the case into Savings goal and use the five-month plan as the baseline. The comparison cards let you explore two or eight months while holding the amount and starting balance fixed. Download the CSV to inspect each deposit. This schedule does not pay the bill, reserve money in an account or evaluate whether the monthly commitment fits your wider budget.