One register, whatever the contract model
The register is the client's tool, not the contractor's. The contractor keeps its own variation lists, from its own point of view and with its own amounts. The client needs a list that shows the client's assessment and is reconciled with every interim invoice.
It applies equally to contracts under the BGB and under the VOB/B, even though the legal bases differ. Under a contract governed by the Bürgerliches Gesetzbuch (BGB, the Civil Code), variations arise mainly through the right to order changes under ss. 650b and 650c BGB, explained in the article on changes under section 650b BGB. Under a VOB/B contract, they arise through s. 2(5) and (6) VOB/B, set out in the article on variations under section 2 VOB/B. The register translates both into the same language: amount, status, date.
The register's columns
Twelve columns are enough if each is filled in consistently. Fewer means questions cannot be answered in a dispute; more means the register stops being kept up to date.
| Column | Content | Why |
|---|---|---|
| Number | consecutive, never reassigned | clear reference in correspondence and invoices |
| Trade and contract | contract affected, items | link to the contract sum |
| Origin | change ordered by the client, design change, necessity reported by the contractor | responsibility and source in the budget |
| Contractual basis | s. 650b BGB, s. 1(3) or (4), s. 2(5) or (6) VOB/B | applicable rules on price and form |
| Date of request or order | receipt by the contractor | deadlines, in particular the 30 days under s. 650b(2) BGB |
| Date of notice | contractor's notice of the claim to pay | duty under s. 2(6) no. 1 VOB/B |
| Date work started | actual start of the changed work | comparison with notice and agreement |
| Amount offered | contractor's claim, net | starting value, basis of the 80 per cent interim payment |
| Amount assessed | own assessment by the client or its representative | probable value for the forecast |
| Amount agreed | price agreed in writing | fixed value |
| Status | instructed, notified, disputed, rejected, withdrawn | allocation to a line of the forecast |
| Consequences | effect on programme, fee consequences for the designer | side effects on budget and programme |
The date columns are not bureaucracy. A dispute over a variation is almost always about facts: who asked for the change, when, whether the pay was announced in advance, whether it was negotiated before execution. Whoever records these dates as they arise does not have to reconstruct them later.
The anchors in the VOB/B and the BGB
Under a VOB/B contract, the price should be settled before execution. For changes to the building design and other orders, s. 2(5) VOB/B provides that a new price is to be agreed taking account of the extra or reduced costs; "The agreement should be made before execution" (unofficial translation, as are all quotations here). For required work not provided for in the contract, under s. 2(6) no. 1 VOB/B the contractor is entitled to special pay; "However, it must announce the claim to the client before it begins to carry out the work."
For the register this means recording notice, agreement and start of work separately. What legal consequences a missing notice has in a given case is a question of interpreting the VOB/B, dealt with in the article on s. 2 VOB/B. The register simply ensures that the facts are available.
Under a BGB contract, the law provides a fixed procedure. The change request is followed by an offer from the contractor; without agreement within 30 days, the client can order the change in text form. If no agreement on the amount is reached, the contractor can apply 80 per cent of the extra pay stated in its offer in interim invoices (s. 650c(3) BGB); overpayments must be repaid with interest. The register therefore needs the amount offered as well as the amount assessed, because the former determines liquidity.
The three statuses and their lines in the forecast
Every variation sits on exactly one line of the dashboard described in the article on forecasting the final cost during construction. The status decides which.
| Status | Meaning | Amount in the forecast |
|---|---|---|
| instructed | price agreed in writing, or change ordered and assessed | agreed amount; for a change ordered without agreement, the assessed amount |
| notified | claim or offer received, review under way | assessed, probable amount |
| disputed | claim rejected in whole or in part, dispute open | assessed, probable amount |
| rejected or withdrawn | claim settled | zero, entry stays visible |
A disputed variation stays in the forecast at its probable amount. Removing it because the client considers the claim unfounded means betting on the outcome of a dispute. The probable amount is an estimate, adjusted with every new piece of information, not an acknowledgement.
Items received without an amount get an estimate. A notified variation for which no offer has yet arrived is entered in the register with the client's own estimate. An empty field is read as zero in the total, and that is exactly the error the register exists to prevent.
Reduced costs with the same weight
Omitted work that is not deducted is a hidden variation. Both s. 2(5) VOB/B and s. 650b BGB speak of extra or reduced costs, or of extra or reduced pay. Recording only claims for extra pay overstates the effect of savings and overlooks the fact that a contractor could continue to bill an omitted item.
Reduced costs get their own number and the same status sequence. A saving the client has decided on is in the budget only once the deduction has been agreed or assessed.
A fictitious worked example
The following example is entirely invented and serves only to show the arithmetic. A project has contract sums of EUR 2,400,000 net. The budget provides a contingency of EUR 120,000 for variations.
| Variation group | offered | assessed or agreed |
|---|---|---|
| instructed, extra costs | 110,000 | 100,000 |
| instructed, reduced costs | -15,000 | -15,000 |
| notified | 60,000 | 45,000 |
| disputed | 40,000 | 20,000 |
| Total | 195,000 | 150,000 |
The forecast from variations stands at EUR 150,000, that is EUR 30,000 above the contingency. The overall forecast excluding quantities and price adjustment is EUR 2,550,000 (2,400,000 plus 150,000). The warning appears even though only EUR 85,000 has actually been instructed: anyone looking only at instructed variations sees a contingency with EUR 35,000 still free (120,000 minus 85,000) and misses the overrun.
The disputed variation has a different effect on liquidity. If it is an offer under s. 650b BGB without agreement on the amount, the contractor can apply EUR 32,000 (80 per cent of 40,000) in interim invoices, more than the EUR 20,000 the client considers probable. Here the forecast and the payment plan diverge, and both must be visible.
Two invoices per change
A change with the contractor often triggers a second one with the designer. Whoever designs a change provides additional services; for architects' and engineers' contracts, s. 650q(2) BGB refers to the fee calculation rules of the HOAI for change orders. How the fee is adjusted after a change of scope is explained in the article on changes of scope and fee adjustment. In the register, this consequence appears in the last column and as a separate entry in the designer budget.
Who keeps the register and who decides
The designer, the project control function or the client itself can keep it; the client must decide. Cost control in work phase 8 is a basic service of the lead designer under Annex 10 of the HOAI. But approving a variation is a spending decision. An internal rule with amount limits for approvals, laid down in writing before construction begins, prevents variations being promised on site before they are in the budget.
The register is part of checking interim invoices. Every interim invoice is reconciled with the register: if the contractor bills variations that the register does not show as instructed, that is the moment to clarify them. Quantity variances without a change, by contrast, are not variations and belong on a line of their own; the article on quantity variances and final cost deals with them.
This article reflects the state of the rules at the date of checking and is for professional guidance. It does not replace legal advice or examination of the individual case.