Zakaat on retirement annuities

Asaalamu alaikum WRB.
Question is regards Retirement Annuities.
I understand RA is permissable.
How to calculate Zakaat on the RA
If I have had the RA for say 10 years and have been paying a monthly sum of say R 300.
In past I have been taking the sum paid by me and paying zakaat on that amount. ie : after ten years I would have paid R 36000 in instalments — so I paid R900 zakaat on the 10th year.

1. Was this correct.

2. Also is it not the correct method to calculate using the surrender value as at the year of calculation? ( Thats the amount they pay to you on your request anytime during the term – paid next day to you if requested.)

3. Or is it correct not to pay any zakaat until I actually get a draw on the RA or when it finally pays out at retirement age? (ie: when I get control of the lump sum or part thereof?)
If this is correct method – do I pay only after one year or immediately it comes in? Is it correct not to pay at least the surrender value or the amount paid in…thats yours like a strong loan is
yours and you pay the zakaat on a strong loan you gave someone?
May Allah reward you.
JazakAllah