Questions & Answers about Mi ingreso sube este mes, por lo tanto voy a ahorrar más.
Both are possible; it depends on what you mean.
Mi ingreso (singular) treats your income as one overall thing: your total income.
- Roughly: “My income goes up this month…”
Mis ingresos (plural) treats income as multiple sources or payments (different jobs, clients, etc.).
- Roughly: “My sources of income / my earnings go up this month…”
In everyday speech, many people say mis ingresos when talking about money in general, but mi ingreso in the singular is also correct and natural if you think of “income” as a single amount.
Ingreso is a polysemous word; it has several meanings, depending on context:
- Income / earnings (financial meaning) – that’s the meaning in this sentence.
- Entry / admission – e.g., el ingreso a la universidad (admission to university).
- Joining – e.g., el ingreso al ejército (joining the army).
Because the sentence mentions ahorrar más (save more) and speaks about a monthly change, the financial meaning income is clearly intended here. Context disambiguates it.