OpenAI has introduced GPT-5.6 Sol, a flagship reasoning model designed for complex professional workflows, featuring a significant reduction in API costs. Specifically, input pricing has dropped by 20% to $4.00 per 1M tokens, while output pricing has seen a 33% reduction to $20.00 per 1M tokens. The model supports a 1,050,000 context window and a maximum output of 128,000 tokens, with a knowledge cutoff of February 16, 2026. Technical capabilities include multimodal text and image input, with text-only output. Developers can adjust reasoning effort across six levels, ranging from "none" to "max." The model supports advanced features like structured outputs, function calling, and various tools including web search, code interpreter, and computer use. While standard inputs are priced per token, prompts exceeding 272K input tokens incur a surcharge of 2x for input and 1.5x for output. Additionally, cached inputs are available at a reduced rate of $0.40 per 1M tokens, though cache writes are billed at 1.25x the standard input rate. This promotional pricing is scheduled to remain active until at least November 21, 2026.