Money can be a touchy subject, so how you approach it with others may take some extra thought and consideration. And although everyone has different levels of comfort when it comes to how they approach finances with friends, family and people they are doing business with, some behaviors are outright rude no matter who you are dealing with. Here are nine rude money habits you need to break now:

1. Asking How Much Someone Paid for Something That You Have No Intention To Buy
   It’s not polite to just ask prices of things, some people love sharing costs, but unless it is offered, that is private information. The exception to this rule is asking about pricing for something you are interested in purchasing. So, for example, it can be appropriate to open a conversation about how you’ve been looking for X and wonder what range a friend paid for a similar item.
2. Discussing Salary
   It’s rude to ask how much money someone else makes, and it’s also disrespectful to share how much money you make unless there is a good reason to do so, i.e., someone is looking for a job in your field and wants to know a typical salary range. But, again, this can make people feel uncomfortable.
3. Asking To Borrow Money From Friends
   Asking a friend to lend you money is an etiquette no-no. You may borrow money from a family member under certain circumstances, but if you do, have a written plan and timeline to pay it back and offer to pay a small interest rate or whatever the lender stipulates.
4. Telling Someone They Spend Too Much Money on X
   How people spend their money is not yours to judge, so you should keep comments to yourself if you think your friend consumes too much money on shoes or your neighbor spends too much money on toys. It may be your neighbor has a lot of recreational items, but that’s not any of your business. Everyone has different spending habits. Some people spend their money on toys, others on vacations, some folks are penny pinchers. There is no right or wrong.
5. Not Tipping at a Restaurant
   When you do not tip appropriately at restaurants is even ruder than usual in our current economic climate, with many restaurant employees out of work for long stretches of time over the past year. If you were unhappy with the service, you may leave a lower tip, but you should not skip tipping altogether. Keep in mind the waiter isn’t always at fault. It could be the kitchen was backed up or made a mistake that the waiter had no control over.
6. Contributing Fairly To a Potluck
   Bringing just enough to cover yourself or one cheap item is considered rude if you’re invited to a potluck. On the other hand, it’s polite to bring value that others can enjoy. A couple of beers won’t go far. Showing up with just a bag of chips is also rude when others are bringing full dishes.
7. Pay attention to the price per unit
   It’s easy to get excited when the foods you like go on sale, but the best way to identify a bargain is to look at the per-unit price that’s usually listed on the shelves. Sometimes, sale items are more expensive than products being sold at regular prices. So, don’t fall for the hype.
8. Not Offering To Pay for Gas When Someone Gives You a Ride
   Especially on longer trips, it’s rude not to pay for gas if someone else is driving. It can also be rude not to offer for shorter trips if it becomes a habit. Someone who asks for a ride all the time but never offers any money for gas is a no no.
9. Not Paying for a Meal You Invited Someone To
   If you offer to take a friend out to dinner or lunch, you should pick up the tab. Whoever invites the other is the one who pays the bill, unless you agree to split it in advance. Please don’t think someone will cover for you

Reference
https://www.msn.com/en-us/money/personalfinance/rude-money-habits-you-need-to-break-now/ss-AAQUEVy/.