Guiding investments by horizon is one of the four Lean budget guardrails that describe the policies and practices for budgeting, spending, and governance for a specific portfolio. This guardrail helps ensure that the portfolio allocates its budget to solutions that reflect different time horizons and risk profiles, balancing near-term opportunities with long-term strategy and growth1. The portfolio-level guidance for investments by horizon is based on the four horizons model2, which categorizes solutions into four types: Horizon 0 (solutions that are being decommissioned), Horizon 1 (solutions that are mature and generate most of the current revenue), Horizon 2 (solutions that are emerging and have high growth potential), and Horizon 3 (solutions that are exploratory and have high uncertainty). Each value stream should allocate its budget to solutions in these horizons according to the portfolio’s vision and roadmap1. References: 1: Lean Budget Guardrails - Scaled Agile Framework2: Investment Horizons - Scaled Agile Framework