Minimum Top-up
The minimum top-up you can make to any CIRCA5000 is £5 (with the exception of Round-ups.)
This applies to both a one-off top-up and a monthly top-up.
Maximum Top-up for a GIA
There is no maximum amount you can add to a CIRCA5000 GIA.
Some banks might have their own card payment limit; so if you're trying to add more than your bank will allow in a single top-up, then you may need to make several smaller top-ups.
Maximum Top-up for an ISA
ISA rules mean you can only add up to the ISA allowance per tax year across all of your ISAs.
The ISA allowance for the 2021-22 tax year is £20,000; so you cannot add more than this amount to your CIRCA5000 ISA for this tax year.
Please be aware some banks may have their own card payment limit; so if you're trying to add more than your bank will allow in a single top-up, then you might need to make several smaller top-ups.
You can read more about ISAs here: https://www.gov.uk/individual-savings-accounts.
Maximum Top-up for an Junior ISA
JISA rules mean you can only add up to the JISA allowance per tax year across your child's JISAs.
The JISA allowance for 2021-22 is £9,000, so you cannot add more than this amount to your child's CIRCA5000 JISA for this tax year.
Please be aware some banks may have their own card payment limit; so if you're trying to add more than your bank will allow in a single top-up, then you might need to make several smaller top-ups.
You can read more about JISAs here: https://www.gov.uk/junior-individual-savings-accounts.