Married couples: a scenario-based tax planning checklist

The income split is usually the biggest driver. Compare outcomes at your current split, then test a few nearby splits to see whether the best option stays stable.

If you have rental profit or one-off income, test those separately. Small additions can sometimes flip the best option if they push one spouse into higher marginal bands.

If the gap is small, sanity-check with the married salary calculator and the PAYE/USC/PRSI breakdown topics. This helps you understand what is driving the estimate rather than relying on a single number.