Bid Alternates in Construction: Additive, Deductive, and Alternate Prices
Bid alternates are optional scope items that owners ask bidders to price separately from the base bid. They let an owner compare the cost of adding, removing, or substituting work without asking every contractor to prepare a new proposal after bid opening.
Direct answer: an alternate price is the amount shown on the bid form for a specific alternate. It may add cost, deduct cost, or replace one scope item with another. In construction search intent, alternate prices should map to bid-form alternate pricing, not to a generic pricing page.
Use this guide when you need to understand additive alternates, deductive alternates, substitution alternates, owner instructions, bid form language, and the pricing checklist that protects your estimate.
Alternate Price Meaning
An alternate price is a separate price for a named alternate in the bid documents. The bid form should tell you whether the alternate is:
- Additive: add this amount if the owner accepts the alternate.
- Deductive: subtract this amount if the owner accepts the alternate.
- Substitution: add or deduct the net price for replacing one system, product, method, or scope item with another.
Do not assume every alternate is optional in the same way. The instructions to bidders may control ranking, award, acceptance order, timing, and whether voluntary alternates are allowed.
Additive vs Deductive vs Substitution Alternates
| Alternate type | What changes | Simple example | Main estimating risk |
|---|---|---|---|
| Additive alternate | Adds optional scope | Add site lighting at the overflow parking area | Missing general conditions or schedule impact |
| Deductive alternate | Removes scope from the base bid | Delete landscaping and irrigation from the contract | Deducting too much and losing margin |
| Substitution alternate | Replaces one system or product | Substitute one flooring system for another | Missing related trade and coordination impacts |
| Voluntary alternate | Contractor-proposed option, if allowed | Offer a different product or phasing method | Bid rejection if unsolicited options are not permitted |
How to Price a Bid Alternate
- Read the alternate description and bid form instructions.
- Identify every affected drawing, spec section, trade, and bid item.
- Build a separate quantity takeoff for the alternate.
- Request separate subcontractor prices for base bid and each alternate.
- Add material, labor, equipment, subcontractor, supervision, and general conditions impacts.
- Check whether the alternate changes the schedule, phasing, access, or bonding amount.
- Apply markup based on the alternate's actual risk.
- Enter the price exactly as the bid form requires.
- Keep the alternate worksheet with the final bid file.
Bid Form Review Matrix
| Bid form instruction | What to check | Why it matters |
|---|---|---|
| Alternate numbering | Does the bid form require Alt 1, Alt 2, and so on? | Misnumbered alternates can make review difficult or nonresponsive |
| Add or deduct language | Does the owner want a positive amount, negative amount, or words such as add or deduct? | Wrong signs can reverse the intended price |
| Acceptance order | Are alternates accepted in listed order or owner's selected order? | Pricing strategy changes if early alternates are more likely |
| Ranking method | Is award based on base bid only or base plus selected alternates? | Ranking rules affect how alternate prices may influence award |
| Voluntary alternates | Are contractor-proposed options allowed? | Unsolicited options can be ignored or create bid risk |
| Time impact | Does the alternate require additional days or a separate schedule note? | A price without schedule impact may be incomplete |
Example Alternate Pricing Worksheet
| Line item | Base bid | Additive alternate | Deductive alternate |
|---|---|---|---|
| Direct material | Included | Add alternate material cost | Remove deleted material cost |
| Direct labor | Included | Add labor hours for new work | Remove labor hours no longer required |
| Subcontractor quote | Base scope quote | Separate add price from affected subs | Separate deduct price from affected subs |
| General conditions | Base duration | Add only if duration or supervision changes | Deduct only if duration truly decreases |
| Markup | Base markup | Apply risk-appropriate markup | Do not over-deduct margin unintentionally |
This table is a framework, not a universal rate. Use your project documents, subcontractor quotes, and company estimating standards.
Common Alternate Pricing Mistakes
- Pricing alternates as rough percentages instead of separate scope items.
- Missing trade impacts created by a substitution alternate.
- Forgetting schedule, phasing, access, or supervision costs.
- Failing to obtain separate subcontractor alternate prices.
- Entering a deductive alternate with the wrong sign on the bid form.
- Adding voluntary alternates when the bid instructions do not allow them.
- Treating a bid alternate as a change order after award without checking contract language.
Internal Links for Bid Review
Use these related resources before final submission:
- Bid package risk scanner: check addenda, alternates, bid bonds, forms, signatures, and scope gaps.
- Construction bid document checklist: review required documents and final forms.
- Construction bid management software comparison: compare tools for tracking documents, deadlines, and bid status.
- Construction RFI process guide: clarify unclear alternates before the question deadline.
- Change order request generator: document post-award scope changes separately from bid alternates.
Frequently Asked Questions
What is a bid alternate in construction?
A bid alternate is a separately priced option that lets the owner add, remove, or substitute work after bids are received, subject to the bid documents and procurement rules.
What does alternate price mean?
Alternate price means the separate amount entered for a specific alternate. It may be an add price, deduct price, or net substitution price depending on the bid form.
How do additive alternates work?
An additive alternate adds work to the base bid. If the owner accepts it, the contract amount increases by the alternate price, subject to the award rules in the bid documents.
How do deductive alternates work?
A deductive alternate removes work from the base bid. If the owner accepts it, the contract amount decreases by the alternate price or deduction shown on the bid form.
Should alternates include overhead and profit?
Yes, alternates should include the direct costs, subcontractor impacts, supervision, general conditions, risk, overhead, and profit needed for that specific alternate unless the bid documents require a different format.
Can owners use alternates to change the low bidder?
Rules vary. Some instructions rank bids on base bid only. Others rank bids based on base bid plus selected alternates. Read the instructions to bidders before assuming how alternates affect award.