The best financial decision is sometimes refusing a lifestyle increase.

Not raising your spending when your income rises is one of the few financial moves entirely within your control. Every increase you decline to absorb turns directly into margin, and margin is what buys the ability to leave a bad job, take a risk, or handle a shock without disruption. Nothing else does that as reliably.

When your income next changes, hold your fixed costs where they are for six months. Decide afterward, with the money already accumulated, what if anything is worth raising.