Money or any other thing due to the defendant absolutely and without any contingency may be so attached before it has become payable, but the trustee shall not be compelled to pay or deliver it before the time appointed by the contract.
Mass. Gen. Laws ch. 246, § 24
Money, etc., due but not payable; attachment
Official source: Massachusetts Legislature. Reproduced from public-domain Massachusetts statutes; confirm against the official source for the current text. Not legal advice.