The mutual had previously only been accepting mortgage applications to a maximum of 80 per cent LTV after returning from the lockdown.
The products are available to first-time buyers, home movers and remortgage customers, offer a free standard valuation on properties up to £500,000 and allow 10 per cent overpayments per year.
Deals include a two-year fix at 2.85 per cent with a product fee of £999, while a fee-free version is at 2.99 per cent – both have early repayment charges.
John Truswell, head of intermediary mortgages at Newcastle Building Society, said: “We’re pleased to be extending our current offering to 85 per cent LTV and increasing our support across the market for first-time buyers, home movers and existing home owners looking to remortgage.
“We pride ourselves on our customer service and brokers can be assured their clients will receive the highest levels of service for mortgage applications and processing.”