LLM prompt design & eval for QuickBooks' deduction maximizer

I edited the production LLM prompt for QuickBooks' tax deduction maximizer to ensure trust and quality.

Spreadsheet comparing deduction suggestions per industry between prompt versions

Improving lacklustre generic results

When testing QuickBooks' deduction maximizer in a pre-production environment, the suggested deductions felt very generic and impersonal. This was very likely to affect the feature's engagement and success metrics.

I decided to rework our production LLM prompt to ensure:

  • the deduction names were specific enough to each customer's industry that they felt tailored;
  • the top three deductions per industry were 'safe bets' the business owner was likely to have missed or not know about.

I did that through zero-shot prompting and guidelines based on insights from research I performed with customers and tax advisors.

Evaluating model ROI

Another decision I drove was about the model used in production: cheap versus frontier.

I ran our 10 most frequent industries across all the models we were considering to evaluate the quality of their outputs. I scored the outputs on personalization and relevance, based on what I knew from the research I had performed earlier with customers and tax advisors.

I was then able to present the team with a recommendation of which model to use, based on output quality, and to justify the investment in a higher-quality, more expensive model.

Deduction optimizer scores by industry across GPT 4.1, GPT 5.0, Gemini Pro and Claude Opus