Married filing jointly is what you will now do for taxes for the year 2023, assuming you get married this year. If anything, it will afford you a bigger tax refund this year.

A prenup is probably unnecessary as neither of you have assets to protect.

The other partners debt will only affect the other spouse if you apply jointly for credit, such as for a mortgage. Work to pay off your debts ASAP together.

SMART MOVE on the cheap wedding, hats off to ya. Make it a special day, but don't blow a fortune.

I'm a big proponent of joint finances, unless you have any doubts about the long term stability of your marriage. Which, if you're getting married, I hope you wouldn't have, but some people do I guess. Keeping joint finances is great because there's never a question of who pays what, or "his" vs "hers" or whatever. It's OURS. OUR bank account, OUR finances, OUR taxes, OUR cars, OUR debts, OUR credit cards.

Talk in depth about your financial perspectives, goals and dreams, and then hold each other accountable to them. Too many marriages fail because of financial problems, but if you both can be adults about it, you can build wealth together.