How to learn to read handwritten Kanji

Hello,

I work in a Japanese company and my Japanese is somewhere close to business Japanese. I am still studying Kanji, but manage to be able to read most of them in the field I am working for. My problem is that every time a colleague pass me a note he wrote, I cannot read anything, even the words and Kanji I have normally no problem reading in printed form. When I ask another co-worker he has no trouble at all reading it and it is quite embarrassing for me. The thing is even after he told me what it is, it is really hard for me to see the similarities between the printed and handwritten Kanji. I know that Japanese tend to make shortcuts wherever they can when writing Kanjis, but it is completely a mystery how another Japanese person has no problems to read it.

Do foreigners who are nearly perfect at Japanese still have problems to read handwritten Kanji as well? and does anyone have some tips how to learn to be able to read handwritten Kanji?

My non-Japanese husband, who reads the local newspaper every day and does translation (from Japanese) as profession, cannot decipher my handwriting unless I write it really big and clear, and declines work requests for handwritten faxed notes for example.

Handwritten kanji are, by far, the most difficult type of Japanese text to read. Kanji are the most complex form of text (i.e. they've got the most strokes per character), so any quirks of a person's handwriting get multiplied that many times. The even bigger problem is that no two people's handwriting is exactly the same, so essentially you're always seeing each handwritten kanji for the first time.

I don't have any magic method to improve handwritten kanji reading skills, other than to simply practice/study as much as you can with kanji, and Japanese, in general. Being able to read handwritten kanji is often a result of your brain knowing what any particular kanji both could or couldn't be, and then your brain knowing what make sense.

As a simplified example, if I was looking at a handwritten sentence with one kanji I couldn't read (represented by ◎) that looked like this:
とてもお腹が空いているので、焼◎を食べたい
I'd probably think "Hmm...焼◎ has to be some kind of noun, since it's followed by を. The person is hungry, so they probably want to eat something filling, so what's a filling food that starts with 焼? Oh, yakiniku/焼肉. OK, so does the kanji I can't read look like maybe it's 肉? Yeah, it kind of does. OK, then ◎ must be 肉."

That probably sounds incredibly complicated, but the more experience/practice/study you get with kanji, and Japanese in general, the quicker the process becomes, and eventually it can become pretty much automatic, as your brain learns what is and isn't possible based on existing vocabulary, grammar rules, and context.

As another example, my wife (native Japanese speaker) and me (native English speaker) both have pretty similar eyesight. However, if we're walking around Tokyo, she can read street and shop signs (that are in Japanese from much farther away then I can. When we go to Los Angeles, though, the phenomenon flips, and I can read English sings from farther away than she can. There's no real difference in our eyesight, though. It's just a result of our respective language skill levels being able to decipher what hard-to-see/decipher text is by non-visual methods.

Reading Kanji OK
Write Kanji OK
Reading handwritten Kanji NG

This is even after long practice difficult, but trying often and asking often is the only way you can do.

「declines work requests for handwritten faxed notes for example」

Translating from handwritten kanji is definitely a more time-consuming project. I work in translation management, and we generally have to allot more time/charge more for handwritten source materials.

In my experience the best way to learn to read Japanese is to learn to write Japanese. I had the same problem until I learned to write too.

I think, because you can't write kanji properly, you can't read handwritten kanji.
it is easy to read printed kanji. but, it is difficult to write it by hand. you skip this practice by using computer.
in Japan, pupils in elementary school learn how to write kanji thoroughly.

Here is unique application.
https://nge.jp/2016/12/11/post-136707