How should I invest in SSB ?If i want to put it for max 10years, what is the difference if i put in $10k at once between buying $1k every year for example?

If you already have the $10k now, I would suggest to split this $10k over 6 months. Say for example, $1.5k a month (can only do multiple of 500) for 6 months. As SSB pays interest every 6 months, this will allow you to have an interest income every single month for the next 10 years.

Of course, you can also choose to do $1k per month for 10 months. You will also get the monthly interest income too.​​​

I would prefer to put all in 10k if you are comfortable with it as the interest for ssb will change every month so you might get a lower interest in the following month.