The GHG Protocol uses "reasonably close to the reporting year" to set how old an Energy Attribute Certificate (EAC) can be when matched against your energy consumption. It's a core requirement for Scope 2 market-based accounting, and the specific rules depend on where you're operating. In the EU, national regulations under the RED III framework govern when Guarantees of Origin (GOs) can be issued and cancelled. Outside the EU, the GHG Protocol sets a twenty-one-month vintage window: generation from six months before to three months after the reporting period. This window applies to whichever EAC type you're procuring, whether that's North American RECs, UK REGOs, or I-RECs in emerging markets. Cancellation (or redemption, in REGO terminology) happens through the relevant registry or via Soldera Virtual Accounts to streamline the process across different certificate types. The vintage timing is worth getting right. Certificates outside this window simply won't count toward your Scope 2 claims. Auditors check vintage dates, and getting this wrong means your renewable energy claims don't hold up, or worse, you get flagged for double-counting.