It has one product specifically for first-time buyers and two for purchase applications.
The first-time buyer deal is fee-free with an initial rate of 3.81 per cent, free standard valuation and £500 cashback.
The two purchase products are for loans above and below £350,000, both with a rate of 3.76 per cent.
The smaller version has a fee of £900 and the larger loan option has a fee of £1,200.
David Castling, director of intermediary lending at Atom said: “We continuously evaluate the mortgage market and believe it is in our customers’ best interests to apply a considered approach to the products we offer.
“We now feel it’s the right time to get back in the market with 90 per cent LTV to support first-time buyers and homeowners.
“The world is a different place in light of Covid-19 and we need to make sure we can give customers choice while also lending responsibly. Given the ever-evolving landscape, we have taken the decision to reintroduce these products.”