Modern Splashes & Other Variants
In Modern, each color has a corresponding variant of Death and Taxes. Some lists, like RW Taxes, are more fine tuned and powerful than other lists, like BW Taxes. However, each color configuration adds a fair number of creatures that fit well into the Death and Taxes shell.
The most common of variation of Death and Taxes without necessarily splashing a color would be adding Eldrazi to the deck. Two main versions of that deck exist: one with black, and one without. The final variation of Death and Taxes in modern is one that not only uses Eldrazi, but also drifts away from the traditional Aether Vial build and instead opts to use Chalice of the Void as a lock piece.