"In this world nothing can be said to be certain, except death and taxes."This was apparently written in a letter to Jean-Baptiste Leroy, 1789, which was re-printed in The Works of Benjamin Franklin, 1817.
Before that however Daniel Defoe used a similar phrase in The Political History of the Devil, 1726:
"Things as certain as death and taxes, can be more firmly believed."And much more recently Margaret Mitchell says the following in her book Gone With the Wind, 1936:
"Death, taxes and childbirth! There's never any convenient time for any of them."