An AI coding budget under $100: make Claude and Codex work together

Buy a second perspective before buying duplicate capacity

For intermittent coding, a $40 pair is a useful starting experiment: Claude Pro for daily discussion and a second review, Plus for Codex implementation. This is a workflow recommendation, not evidence that two entry plans outperform a $100 plan. If one allowance repeatedly interrupts your main work, concentrate the budget there.

A $20 Codex plus $100 Claude combination costs $120 before tax. It belongs in the larger-budget guide; it cannot fit under $100 by changing how the models are used.

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A normal day: one executor, a second opinion when it matters

Choose versions actually available in the client. Claude Code supports Sonnet for daily work, Opus for deeper reasoning and opusplan for Opus planning followed by Sonnet execution. Sol 6.1 access and controls depend on rollout. These roles are a starting arrangement, not a measured winner for every repository.

Why these roles? The published Sonnet 5.5 Max configuration scores 56 on AA’s composite and 63.6% on Terminal-Bench 4.0; Sol 6.1 High scores 50 and 51.5%. Sonnet deserves consideration for substantive work, while Sol’s lower average API task cost supports a bounded-execution trial. Those figures do not establish Medium performance or how long either $20 subscription lasts. The linked larger-budget guide explains the configurations, method and tradeoffs.

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• Read the exact rankings and what they justify

Try the arrangement on one feature

• Ask Claude to turn “add a provider submission form” into required fields, validation rules, abuse controls and acceptance checks. Stop at an implementable brief.
• Give Codex the agreed brief and relevant files. Ask it to implement the smallest complete change and return the diff, test results and remaining limitations.
• For this public submission path, ask Claude to review validation, duplicate submissions and failure states. Return specific findings to Codex; do not ask both to rewrite the feature.
• For a simple copy change, skip this chain and use one tool. Cross-model handoff should solve a real uncertainty.

Upgrade the subscription that interrupts completed work

After a week, record accepted tasks, time spent correcting them and interruptions from each allowance. When Codex is the bottleneck, move some implementation to Claude before buying more capacity; reverse the arrangement when Claude is constrained. A model that remembers the task may finish faster than a fresh handoff.

The remaining $60 is not a spending target. Keep it for tax or a demonstrated need. ChatGPT Work and Codex share plan usage; Claude chat and Claude Code share subscription limits. A second client does not create another allowance. API calls are separately billed and do not automatically consume these subscription budgets.

• The $120 Claude + Codex workflow, within a $200 ceiling