Grieving spouses may be unaware of an additional allowance that can help them save tax-free beyond the standard annual Isa limit. The Additional Permitted Subscription (APS) allows individuals to contribute funds from a deceased spouse or civil partner's Isa wrappers into their own Isa, regardless of their personal annual allowance.

To utilize the APS, savers must first obtain a certificate from the original Isa provider detailing the amount of the extra allowance. This allowance can then be used to open a new cash Isa, either with the original provider or another institution that accepts such subscriptions. However, not all providers accept APSs, and information about this can be difficult to locate.

Rates for APS accounts can sometimes be significantly lower than those offered on standard easy-access Isa accounts, often yielding less than 4 percent. While it might seem easiest to stay with the deceased partner's original provider, this could result in lower returns, particularly if the Isa was held with a major bank or building society.

Some institutions offer dedicated Isas for APSs, but these may come with poor rates. Others only allow the funds to be placed into their standard easy-access accounts. For example, Nationwide offers its Triple Access Isa at 3.3 percent with withdrawal limitations, dropping to 1.1 percent after a year. Skipton's Legacy Isa and Coventry's Additional Allowance Isa both offer 2.05 percent, while Leeds does not accept APSs at all.

Yorkshire Bank provides more options, allowing APS funds to be placed in their easy-access Isa at 3.6 percent or a one-year fixed-rate Isa at 4.4 percent. Among major banks, Lloyds, Halifax, Santander, HSBC, NatWest, and Barclays accept APSs into easy-access accounts, but rates vary, with Lloyds offering 0.75 percent and HSBC's Loyalty Cash Isa at 3 percent, requiring an HSBC current account. Barclays and NatWest may be suitable for those considering fixed-rate Isas.

For potentially higher rates on easy-access Isas, app-based Trading 212 offers 4.61 percent for the first year, and Virgin Money's Double Take E Isa provides 4.15 percent with two annual withdrawals allowed. The National Savings & Investments Direct Isa pays 3.8 percent.

Once an APS is deposited into an Isa, it becomes a standard cash Isa and can be transferred to other providers in the usual manner.