Couples want cash, honeymoon donations and even IVF — what’s the new wedding etiquette?

In September, a British couple raised eyebrows across social media by treating their wedding guests like restaurant patrons, presenting them with a QR code and a contactless card reader at the reception.

“Don’t be tight, pay for our flight,” the couple signposted, inviting friends and relatives to donate to a Mexican honeymoon.

“People got more generous as the drinks started to flow!” said the 35-year-old groom, Chris Martin. “Some of them even tapped more than once.”

While a few may be shocked by the couple’s unembarrassed approach, experts reveal that when it comes to wedding gifting and registries, tradition has flown the coop and almost anything goes.

“It used to be that you had this big department store registry,” said Veronica Moya, founder of micro-elopement company Wedding Packages NYC and the Love Chapel venue at 8th Avenue and West 56th St. “But nowadays, people already live together by the time they get married, so they don’t need a toaster and a blender and all that stuff.”

Couples are getting hitched older than ever (the average age in the US is now 32, according to a study by the Knot), so requests for donations for fertility treatments are becoming as normal as a honeymoon fund.

“More people are having small, micro weddings,” said Moya. “And when I ask my couples why they didn’t go the traditional big wedding route, I’d say about 40% of the time they tell me about expenses around invitro fertilization (IVF).”

But remember that some of your nearest and dearest might find the request for such an intimate gift face-reddening, if not offensive. Your threshold for TMI is not your aunt Sylvia’s.

Meanwhile, for marrying youths who don’t know the words Wedgwood, Spode or Doulton and shudder at envelopes of money, it’s easier than ever to collect digital “cash” gifts.

At his viral wedding, Martin used a new fee-less service called Lopay for his gift experiment, but Venmo, Square and Zelle are also popular options.

There are also hundreds of competing registry websites to choose from and fill with your wants and needs (Zola, MyRegistery, Honeyfund, Giftful), and each offers slightly different perks. Sorry Grandma, but you’re going to need to follow the link, sign up, scroll, click, enter your card details and fret over shipping.

So are there even any rules left to honor in this new Wild West of wedding registry rigmarole? Thankfully, definitely, yes.

Don’t get greedy

Weddings can have strange effects on otherwise well-meaning people: They turn them into selfish jerks.

“I had this bride who was having her wedding at the Rainbow Room [at Rockefeller Center], which is so crazy expensive,” recalls Moya. “She spent about $500 per guest and she told everyone that she expected them to give accordingly. That’s a big ‘No.’ Your wedding expenses are your choice, not your guests obligations. It was very obnoxious.”

If you organize a registry, it should have a wide variety of options and price points — and be aware that stats show you’ll only get roughly half of what you ask for.

Cash is still king

“People have very strong opinions about cash,” said Sara Margulis, CEO of honeymoon registry website Honeyfund. “But the popularity of cash registries have only grown and now we’re seeing a whole generation of couples that are comfortable just throwing a Venmo QR code on the wedding invitation, on the gift table or on their car as they drive off with the cans on the back.”

Even if you don’t like handling the cold hard stuff, zero-fee websites like Honeyfund make it easy to collect money — just be warned that many take a cut.

And instead of simply collecting money in a pool — which can make attendees feel like they’re paying to be a guest at your wedding — Margulis recommends getting granular.

Let friends and family contribute to specific parts of a trip — like an adventure to a vineyard or a helicopter excursion. The more creative the better. Margulis points to a couple that asked for money towards an entire wheel of Parmesan in Italy.

“When it comes to asking for cash, you want to do it in a way that makes givers excited about an experience that you’re going to have,” said Margulis.

Or, consider fund-raising for a travel advisor’s fee, since “honeymoons are more complicated than they used to be,“ said Kate Lacroix, a Boulder, Colo.-based travel advisor with Fora.

But, Moya warns, don’t act like an influencer: out of touch isn’t a good look.

“Be humble,” she said. “Think of your guests. If they’ve never traveled and you are asking them to pay for you to dance with dolphins, it can be a little uncomfortable.”

Keep it convenient

A good registry has price points that range from $20 to more than $300 and items from a wide variety of easily accessible stores. Aim for at least six.

But one thing couples who use an online registry rarely consider is where the items are physically located and how they’ll be receiving them. Some guests will be happy to ship a gift directly to your home, while others will want to pick it up in-store or ship it to themselves to present in person.

“We found that 30% of all items were purchased within two weeks of the wedding,” said Cono Onorato, founder of Giftful, a wish list and registry platform that lets you keep the gifts hidden until after the wedding. “So there’s definitely a decent percentage of people who are going to be looking for that last minute item that they could pop into a Target and grab.”

In fact, Giftful’s data scientists found that 20% of purchases are made on the same week of the event and 5% on the day of the I do.

“What leaves some registry items unclaimed is that they won’t arrive in time for the wedding,” said Onorato. “A successful registry will be compiled knowing that guests are going to be picking something up on the way to the wedding.”

Boycott your activism

Some couples already have it all or simply aren’t into “stuff.” So it’s no wonder that it’s become so popular to ask for a donation to a favorite charity in lieu of a gift. It’s a nice sentiment and well-meaning, but your pet cause could be someone else’s bugbear.

“Maybe you and your friends are into a particular cause, but that’s maybe 10% of your guests,” said Moya. “I don’t think it feels nice for the rest. Most want to give something to you.”

It should go without saying that your wedding isn’t the moment for political posturing, but even endorsing the most uncontroversial of charitable dot-orgs puts you at risk of coming off a little holier than the rest (remember rule No. 1).

After all, if you really were the paladin of philanthropy you’re pretending to be, you’d donate anonymously for the cause, not the glory.

“Just take the money,” advised Moya. “Then you can do whatever you want.”