as of

Why does a contract state, “This Agreement is dated as of November 27, 2010,” instead of “This Agreement is dated November 27, 2010”? It’s because the magic words, “as of,” refers to the date that an agreement is effective. The “effective date” (or the “as of” date) can be different than the date of signature, so it’s common practice to use “as of” in the preamble to indicate when an agreement was reached and to include a separate date for signatures. Another simple workaround is to state, “This Agreement is effective as of November 27, 2010 (the “Effective Date.”))

See: preamble