Booking a return without knowing your return date - does it work?
 

I need to fly LON-SIN or LON-KUL soonish, coming back I have no idea when but more than 6 months, less than 12 months.

Fees:
LHR PSC/UK APD = £120
KUL PSC = £14

MH fares:
Cheapest return LHR-KUL fare w/3 month max validity + YQ = £438. Total with taxes = £572
Cheapest return LHR-KUL fare w/12 month max validity + YQ = £674. Total with taxes = £808

Cheapest one-way LHR-KUL fare + YQ = £250 or £370 with taxes/PSC
Cheapest one-way KUL-LHR fare (no YQ ex-KUL) = £344 or £358 with taxes
Total return cost for two one-way with taxes = £728

So two one-way tickets works out cheaper, and that's before the £100 change fee for the return, and possibly a fare increase as well.

So does it ever make sense to go for the return when you don't know your return date? Do you ever do it?

You've done the right calculations here, checking both return and one-way fares and considering change fees and validity periods. The answer is that it can go either way. Sometimes a pair of one-way fares are available for about about the cost of a return ticket, in which case it makes sense to book that way. Other times a return is vastly cheaper than two one-ways, and it make sense to book return now and pay a change fee later.

20 years ago, I bought an "open ended" ticket to Europe. Outbound fixed, return simply needed to be confirmed with a 72-hour notice and used within 1 year. (Required availability of course, but it was a medium/high economy bucket and I was able to get what I wanted.)

It was around $800 R/T in an era when one-ways weren't available at all (short of buying full-Y). The discount-Y fare with change fees, taking a guess on an exact return date about 10 months in the future, would have been $700-ish. So I was paying less than a change fee to have the flexibility, and it worked out well. I never see these fares advertised anymore ex-U.S., but maybe they still exist ex-Europe.

The availability of one-ways on most routes these days may have killed the need for them.

I have booked returns the maximum year out allowed several times and then when I was ready to return (under the year) changed the return date accordingly. It all depends on the math obviously and if it makes sense.

I'm not clear on why you are even asking the question. What is the possible down side you are concerned about? The only possible downside I can see is if you in fact did not end up returning before the maximum time expired.

I found this while doing travel planning for this summer:

6/23 PIT-BCN - $2,989

6/30 BCN-PIT - $3,050

6/23-6/30 PIT-BCN-PIT - $1,361

I'm pretty sure the international change fee is less than $4,700.

If you are traveling Internationally, don't you need to show (or have) a return/exit itinerary to enter that country. How will waiting to purchase a return/ongoing flight allow you to enter that country?

That's dependent on the country, your own citizenship, and the type of visa you hold.

When I had my open-ended ticket, I was entering the UK with a US passport and permission to stay 1 year. I don't recall how closely immigration looked at the airline ticket, but I know I handed the agent a healthy stack of paperwork and he looked through some of it. This was in an era when you couldn't easily buy one-ways to begin with, so I'm guessing the agent was used to that type of ticket. Given the ubiquity of one-ways today (at least on on a US-UK route where you could easily show up on Norwegian or something), I don't know whether immigration agents view the fact that you haven't yet bought your return as any kind of concern.

Whenever I enter Europe or the UK without a visa - either short-term business or as a tourist - nobody ever looks at my airline itinerary. Same when I've entered other countries with business visas. Only place I had to show all my paperwork was Bermuda of all places...and I was just going there for the weekend as a tourist. (I had it printed on paper, like I always do...just in case.)

You can just print out a booking typically, though I have an Indonesian residence permit so that's not necessary in my case.

There is a common perception around the issue of 'proof of onward travel'. Many people believe this is always needed when in fact it may not be. Some countries do require you to show proof of onward travel (or return) and some do not. Airlines are far more likely to be who insists on it as they are subject to penalties and having to fly you back to your departure point if you are denied entry into a country.

If you ask an airline if you need a return ticket to the UK for example, the airline may well say, 'yes you do'. Yet there is no requirement for a return ticket in UK Immigration law they can point to as it doesn't exist. What many countries such as Canada (as another example) do have is a requirement, 'to satisfy the Immigration Officer of your intent to leave', or words to that effect. A return or onward ticket can provide some indication of that intent but still isn't proof of intent. The bottom line is if the Immigration Officer 'suspects' your intent, that's all that is required to deny you entry whether you have a return ticket or not. All the return ticket does is cover the airline's butt, not yours.

If you haven't booked the return, there is no booking to show..

I'm unclear on the logic here. What is "3 months validity"? Do you mean returning within 3 months from departure date - beyond that the fare increases?

Because 572+100 is cheaper than 728, and a fare increase for the return would affect both the change of the return fare and the future purchase of the one-way flight back, no?

My travel agent in Indonesia in the past has created a booking for me. I think the booking expires within 48 hours if not paid, so in fact the 'booking' didn't exist when I used it, but it satisfies people asking for a piece of paper.

One other time I created a fully refundable Y class ticket. That was a bit expensive. I wouldn't recommend it. It's better to just get the cheapest outbound single and throw it away.

Or there are other ways with Photoshop or whatever.

Fundamentally, however, the 'return ticket' requirement is a bit silly.

Airlines have different rules but currently the cheap fares on MH must be purchased at least 5 days in advance, have availability in O or Q class, be for a minimum stay of one Sunday, and a maximum stay of 3 months. Also the outbound date must not be in peak season (around Easter, Christmas & July/August). If you don't comply with all of these, the fares go way up.

The £572 fare useless because I'm definitely staying over 3 months. So I'm looking at £808 + £100 change fee.

It's possible for the return fare to change but the one-way flight not to, because there are other airlines - if currently it's £300 on MH, and £400 on SQ, but when I want to fly MH has gone to £500, then I would just book SQ.

The other issue that occurs to me is that if you buy your ticket via a third party booking side you may get a discount. However for a return ticket third party websites are likely to be completely useless if you want to change, as you will get hit with two sets of change fees.

There is no single answer to OP's question. While the utility of "open" tickets has largely gone away, on some routes and in some fare buckets, it may be worthwhile. In other situations, it may not. The only way to come to an answer for any particular situation is to check it out.

Certainly carriers do issue full YY tickets and there are sometimes reasons for those which go beyond immigration requirements. But, these days, it is most often far better to book the return ticket, fly the first segment and then pay the change fee for the second when you know your plans better.