The general rule is that an executor's power of sale can be exercised until "the purposes for which it was given are effectuated or become impossible of accomplishment."  New England Trust Co. v. Morse, 243 Mass. 39 (1922). Although this means that certain powers of sale may never expire, in most cases the power of sale will terminate upon the filing of a final account with respect to the decedent's estate. However, powers of sale have been held to last as long as fifteen and twenty-six years in cases where the terms of the will authorized the executor to defer the sale of certain assets until an economically advantageous time.  See Bayley v. Sloper's Ex'rs, 263 Mass. 534 (1928) and Johnson et al v. Tacey, 326 Mass. 628 (1951).  Despite these cases, attorneys should exercise caution when relying on a power of sale exercised after the filing of a final account.