Build, buy, or combine decision memo

Compare the same capability and acceptance criteria across options. Use requirements that could change the decision; avoid a universal weighted score.

Context

Workflow / users / business owner:  

Decision owner / people consulted (operator, security, finance, adviser where contracts are involved):  

Business outcome expected and how it will be measured:  

Required outcome / constraints (deadline, budget, regulatory or contractual requirements, data sensitivity):  

Standard needs / distinctive needs:  

Expected lifetime of the capability and the comparison period used for cost:  

Skills available to build and to operate each option, and what would have to be hired or bought:  

Options

Order of consideration used (for example, configure what is already owned before buying, buy before building), and where the decision departed from it:  

Assumptions to test

Pilot and acceptance evidence:  

Cost period / effort ranges, including licenses, usage-based fees, integration, and exit:  

What if maintenance rises, scope grows, or a provider changes?  

What if the builder or the key operator leaves?  

Decision record

Selected arrangement / reason:  

Options rejected and the decisive reason for each:  

Consequences accepted (lock-in, ongoing effort, capability not covered):  

Remaining conditions / accepting owner:  

Operating and exit owners:  

Reconsideration triggers / review date:  

Common failure modes

• The build option is costed for delivery and not for the years of operation.
• Distinctive needs turn out to be habits the team would have changed for a good product.
• The comparison period is chosen to favor the preferred option.
• Exit is not tested until the vendor raises prices or the builder leaves.

This memo records the decision. It does not replace the vendor review for a purchased product or the cost worksheet for a detailed comparison.