To be eligible for the account, you must be claiming UC and must have at least £1 of earned income during the month you open the account; once opened you can pay in whether or not you’ve had earnings for a particular month.
You can save a maximum of £50 a month; get a payout at end of year 2 equivalent to 50% of the highest amount you’ve saved. The bonus goes into your bank account not the savings pot - so, if you save the maximum monthly amount and don’t withdraw any, after 2 years you’d get a £600 bonus; and would have £1200 in the account. If you continue to save at £50/month, at the end of year 4, you’ll receive another £600 bonus and have £2,400 saved. Then the account closes and you receive the remaining cash - all amounts are tax free.
You can only open the account once, each adult in a couple can open an account.
You can withdraw money at any point during the 4 years the account is open; the bonus paid at the end of year 2 is based on the highest amount saved during that period (so, if you saved £850 then took out £450 before saving another £350 - the maximum you can save over 2 years - your bonus would be £425 - 50% of the highest balance; if you paid in £30 a month and took nothing out, you’d get £360 bonus at year 2)
From year 2 to year 4, if you continue to save, the bonus is 50% of the difference in savings between the end of years 2-4 - so, if you continue to save at £50/month, it would be another £600. If you put nothing more into the account after year 2, there would be no bonus due at the end of year 4.