The lender said its range was designed to help clients who are newly self-employed.
It added that it had seen positive uptake of its existing range for those who have been trading for up to two years and have a full set of year one accounts.
The Help to Buy range features a pair of two-year fixed rate products at 75% loan-to-value (LTV).
A fee-free option at 2.55% comes with a free valuation and £500 cashback, while one with an £800 completion fee and £199 reservation fee payable up front is available at 2.05%.
Both products allow overpayments of up to 10% per year with an early repayment charge of 2% until 31 May 2019 and 1% until 31 May 2020.
The buy-to-let range includes a two-year fixed rate at 2.99% at a maximum LTV of 75% with no fees, free valuation and £500 cashback.
Again, 10% overpayments per year are permitted with an early repayment charge of 2% until 31 May 2019 and 1% until 31 May 2020.
Newcastle Intermediaries’ head of mortgage distribution Steve Carruthers said: “Following on from the success of the launch of our self-employed product range and feedback from brokers outlining the growing need for support in this market, we’re delighted to expand into the Help to Buy and buy-to-let markets.
“These products will help a wide range of borrowers including first-time and next-time buyers.”