Why your cumulative quantity doesn't match the client's, and how to stop it

Every RA bill carries three quantity columns for each BOQ item: up to date, previous and this bill. The arithmetic is plain. This bill equals up to date minus previous. Yet a large share of returned bills come back because the client's engineer reads a different previous figure from the one the contractor printed.

When that happens, the whole line is suspect. The engineer cannot certify this bill's quantity without first agreeing what was already paid. So the line is held, and with it often the bill.

The rule behind the previous column

The previous column belongs to the client's record. It must equal the up-to-date quantity the client certified on the last bill, whatever quantity you claimed. If the engineer cut 2.20 cum from your last claim pending verification, your new previous figure is the certified one, and the 2.20 cum is claimed again inside this bill with its evidence.

Many contractors carry their own claimed figures forward because that is what their workbook holds. The client carries the certified figures forward because that is what was paid. From that point the two sets of numbers drift, and every later bill repeats the gap.

A worked example

Take item 3.2, RCC M25 in slabs and beams, at a contract rate of ₹8,965 per cum. On RA Bill No. 6 the contractor claimed 338.60 cum up to date. The Executive Engineer certified 336.40 cum and held 2.20 cum for a slab depth query. On RA Bill No. 7 the measured up-to-date quantity is 412.80 cum.

The arithmetic: 412.80 minus 336.40 is 76.40 cum, and 76.40 times ₹8,965 is ₹6,84,926. The difference between the two rows is 2.20 cum, worth ₹19,723. In the first row that money is lost, because the held quantity is never claimed again. In the second row it comes back on this bill, with the revised drawing attached to answer the query.

Where the drift starts

Most mismatches trace back to one of a handful of causes. They are worth checking in this order, because the first two account for most of the trouble.

1. Claimed figures carried forward. The previous column is copied from your last claim, while the client works from its certificate.
2. Split or renumbered items. A BOQ item is split into two (say, RCC in slabs and RCC in beams) and the cumulative quantity restarts at zero on the new lines.
3. Rounding on every bill. Each bill's quantity is rounded before it is added, so the cumulative figure creeps away from a quantity rounded once.
4. Measurements after the cut-off date. A measurement dated the 2nd of the next month lands in this bill in your sheet and in the next bill in the client's.
5. Deductions booked in a different bill. An opening deduction is entered a month after the wall was billed, so one bill is overstated and the next understated.
6. Part-rate items moving to full rate. The quantity is counted again when the balance rate is paid, when only the rate should change.
7. Unit changes. Reinforcement is billed in kg on one bill and in MT on another, and a factor of 1,000 slips.

Rounding, in numbers

Suppose a contract rounds quantities to two decimals and three bills each measure 10.125 cum. Rounded per bill, each becomes 10.13, and the cumulative reads 30.39 cum. Rounded once on the cumulative, 30.375 becomes 30.38 cum. The gap is 0.01 cum per three bills. It looks trivial until it repeats across 60 items and 15 bills, and the engineer has to explain every one of them to an auditor.

The fix is to keep full precision in the measurement record and round only where the contract says to round, usually on the up-to-date quantity of each line. This bill is then the difference of two rounded figures, and it always reconciles.

Split and substituted items

When the client splits an item or approves a substituted item, the history of the original item must travel with it. If 120 cum of the original RCC item was already certified as slab work, the new slab line opens with 120 cum in its previous column. Zero would be wrong. The beam line opens with whatever part of the certified quantity belongs to beams, and the two must add back to the original certified figure.

Write the mapping down once, in a short note on the bill: old item, new items, and how the certified quantity was divided. The engineer then checks one note and never has to reconstruct your workbook.

A five-minute check before every bill

• Put the client's last certificate beside your draft and compare the previous column line by line.
• List every quantity the client held or cut, and decide which ones you are claiming again with fresh evidence.
• Confirm the measurement cut-off date and move anything dated after it to the next bill.
• Check that split or substituted items add back to the original certified quantity.
• Confirm units on steel and any item billed by weight.

Keep a one-page reconciliation for each bill: claimed, certified, held and re-claimed, per item. It takes minutes to prepare and answers most queries before they are raised.

How Tatha Vastu keeps the columns in step

In Tatha Vastu the previous column is filled from the certified figure the client's engineer recorded in the client bill room. Held quantities stay on a list until they are claimed again or dropped. Split items keep a link to the original item, so cumulative quantities carry across without retyping. Measurements keep full precision and round where the work order says.

If you want a second pair of eyes on your last bill, the free bill check compares your cumulative columns against the previous bill and lists every line that does not carry forward.