How to calculate apartment maintenance

In short: add up the month's running costs, take off any income you use to reduce the bill, split what is left between the flats in a way everyone agreed, add the corpus, and round. Use the same method every month so residents can check their bill.

What goes into the bill

Monthly maintenance recovers what the society spent running the building that month, plus any regular amount you put aside in a fund.

• Running costs billed to owners: watchman or security salary, common-area electricity, lift AMC, housekeeping, water tankers and small repairs.
• Not big one-off works. Painting, a new motor or waterproofing usually come from the corpus or sinking fund, or from a special collection, so that one month's bill doesn't jump.
• Income you choose to use to reduce the bill, such as bank interest or hall rent.
• A fixed corpus or sinking-fund amount per flat, if your association collects one.

Step by step

1. Add up the month's expenses that are billed to owners. Call this E.
2. Take off any income you are using to reduce the bill (I). What is left is the amount to share: pool = E − I.
3. Split the pool between the flats: equally, by area or by flat type (see below).
4. Add the per-flat extras: the corpus or sinking-fund amount, and water by meter if you split water separately.
5. Round each flat's total and check that the flats add up to the total.

Worked example: 8 flats, September

Expense	Amount
Watchman salary	₹12,000
Common-area electricity	₹4,350
Lift AMC	₹3,545
Water tankers	₹9,000
Total billed to owners (E)	₹28,895
Gate painting (paid from the corpus, so not in the bill)	₹6,000

The committee uses ₹210 of bank interest to reduce the bill, so I = ₹210 and the pool = ₹28,895 − ₹210 = ₹28,685.

Equal split: ₹28,685 ÷ 8 = ₹3,585.625. Rounded to paise, seven flats pay ₹3,585.63 and the last flat pays ₹3,585.59, so the eight add up to exactly ₹28,685. With a ₹500 corpus per flat, each bill comes to about ₹4,086 when rounded to the rupee.

Here the water tankers are split equally like everything else. If your flats have water meters, you can split the tanker cost by what each flat used instead: see how to split the water tanker bill by meter readings.

Other ways to split

The same pool of ₹28,685, in a building with six flats of 1,100 sq ft (2BHK) and two of 1,450 sq ft (3BHK), 9,500 sq ft in all:

Method	How it works	Each 2BHK	Each 3BHK
Equal per flat	pool ÷ number of flats	₹3,585.63	₹3,585.63 (last flat ₹3,585.59)
By area, share of the pool	pool × flat area ÷ total area	₹3,321.42	₹4,378.24
By area, fixed rate	₹3.00 per sq ft	₹3,300	₹4,350 (collects ₹28,500: ₹185 short)
By flat type	2BHK and 3BHK in the ratio 1 : 1.5	₹3,187.22	₹4,780.83 (last flat ₹4,780.85)

Equal is simplest, and common in smaller buildings where the flats are alike. Area-based splits feel fairer when flat sizes differ a lot. A fixed rate per sq ft is easy to explain but won't match the month's spending exactly, so the society runs a small surplus or deficit that you should keep an eye on. Whichever you choose, record it in your bylaws or the AGM minutes and use it every month.

Corpus and sinking fund

Many associations add a fixed amount per flat each month to a corpus or sinking fund for big repairs. Show it as its own line on the bill and keep it as a separate fund in the accounts, so owners can see how much has been saved and what it was spent on.

Rounding

Either round each flat's share to paise and let the last flat take the few paise left over, so the flats add up exactly, or round each flat's total to the nearest rupee, as most society sheets do. With rupee rounding, the amount collected can differ from the pool by a few rupees; that's normal.

Common mistakes

• Putting a big one-off expense into one month's bill. Pay it from the corpus or run a special collection.
• Forgetting income. Interest and rent are the society's money: decide whether they reduce bills or go to a fund, and say so.
• Billing the same expense twice, or missing one between two bills. Bill each expense once, by its date.
• Changing the method from month to month. Residents trust a bill they can check.

Do it in Socify

Socify's bill wizard does these steps for you. It picks up the month's expenses and income, splits the pool equally, by area or by flat type, adds water by meter and the corpus, rounds, and makes an A4 PDF bill for every flat. Residents see how their share was worked out and pay by UPI.