FX spot date and settlement

In FX, "spot rate" almost always means a forward rate — not the instantaneous rate "now", but the rate for the earliest date funds can actually settle, the spot date. Spot days (settlement days) are the business days needed to deliver cash for a currency (USD = 1, most others 2). A pair's spot date is today plus the pair's spot days, where the pair's spot days are the maximum of the two currencies' spot days — so most pairs settle T+2. This T+2 / max-of-two rule is load-bearing for the cross-rates matrix.

• Spot days / settlement days: business days to deliver cash for a currency. USD = 1; most currencies 2.
• Spot date of a pair = today + spot days of the pair, where the pair's spot days = max(spot_days(ccy1), spot_days(ccy2)). Most pairs are therefore T+2.
• Why it matters: when a derived rate is triangulated through an intermediate currency, the legs of the triangle can have different spot dates. Reconciling them requires interest rates and an interpolation method (see spot rate derivation mechanics), and spot-day mismatches along a derivation path are the root of subtle risk artefacts (see CRM risk).

• Cross-rates matrix (CRM) — the structure that depends on this convention.
• Time Structures and Tenors — settlement conventions, tenors, date rolling.
• Time and timestamps — the system-wide date/time conventions.