Learn French: Il faut qu'une nouvelle taxe finance ce réseau.

For regular -er verbs like financer, the singular forms (je, tu, il/elle/on) and the ils/elles form in the subjunctive are identical to the present indicative. Because it follows Il faut que, finance is grammatically in the subjunctive mood here, even though the spelling doesn't change.

Why do we have to use que and conjugate the verb here, instead of just using an infinitive?

If you don't specify who or what must do the action, you can use il faut + infinitive (e.g., Il faut financer ce réseau = It is necessary to finance this network). But because we need to state exactly what must do the financing (une nouvelle taxe), we have to use il faut que + a specific subject + a subjunctive verb.

Just a quick refresher—why does nouvelle come before the noun taxe here?

Most French adjectives come after the noun, but nouveau/nouvelle (new) is an exception. It falls under the "BAGS" rule (describing Beauty, Age, Goodness, or Size)—these are short, common adjectives that are placed before the noun they describe.

Why is it ce réseau instead of cet réseau?