If the lump sum becomes available at 65, then at age 85 the cumulative total should be roughly equal under either option. The lump sum can also address a near-term financial goal, such as a dream vacation while your health is still good. At 4.0%, a $24,000 lump sum generates roughly $960 a year in interest, or $80 a month, without touching the principal. At 4.5%, that rises to $1,080 a year, getting close to matching the $100 monthly pension payment. One of the biggest drawbacks of a monthly pension is that it typically ends when you do.