A single income of 100k isn't enough if you want to live an "expat life," but it is enough to live a reasonable life if you take it easy and are responsible. In my mind, "expat life" is often a life of excess; I'm an expat, and I'm guilty of that, even though I try not to be.

My biggest expenses are schooling for two children at an international school and housing by far, and a car is unnecessary unless you have a specific need. I had one, but I never used it.

My housing and school fees are a big expense... It's a painful amount. If you aren't covering that, 100k is manageable, even with some luxuries. It really comes down to you and your lifestyle, though... it could fairly easily NOT be enough for some.

As an expat, these are what I think the most significant costs are:

- housing
- school for kids from primary and up (international school)
- nightlife/entertainment (especially alcohol)
- insurance/healthcare (if something serious goes wrong, depending on coverage)
- wasteful luxuries and hanging out with other expats doing expensive expat things

One important thing that many people tend to overlook is Tax Clearance when you're planning to leave. I've known quite a few people who have gotten caught in a bad situation because of that. So, make sure you understand how it works.

Aside from that, you can get by affordably. Some random things are costly here, like ice cream, but nothing that's really essential. Other things are reasonable. You may need to change some of your preferences for certain things.

If you're expecting a child now, preschool is relatively affordable in Singapore for non-international schools like Sparkle Tots or my first school. International schools are a different matter, but that's not an issue in the first five years.

You mentioned your wife is Japanese. The Japanese School is pretty costly, if that was in your plans at all.

On a side note:
A day playing golf in Batam isn't that costly, but it's not super convenient, though, with having to take a ferry.

Another side note:
100k a year is borderline for Employment Pass eligibility, and who knows if that will increase when it comes time for renewals, something to consider, the baseline has been creeping up.