First-time buyers may be able to get an extra £1,000 on top of the £3,000 Help to Buy Isa boost when it launches in December.Newcastle Building Society is planning to allow savers to receive an extra £1,000 from its own Help to Buy product in addition to the government scheme.The plans involve Newcastle Building Society's Big Home Saver Isa, which pays 2.02% AER, subject to the saver making a deposit each month. The extra £1,000 is paid when completing a mortgage with Newcastle Building Society.A Newcastle Building Society spokesperson told Moneywise: "We are supportive of the government's Help to Buy Isa and are currently looking to develop a suitable product. The Isa is consistent with our popular Big Home Saver product, which offers a cash bonus of up to £1,000, after successfully saving for and completing a mortgage with the Newcastle."We are also looking to offer our CustomIsa facility that would enable customers to hold more than one Isa product and split their annual Isa allowance between different Newcastle Cash Isa products and still get tax-free benefits. This would enable customers to hold a Help To Buy Isa and a Big Home Saver Isa simultaneously."The Help to Buy Isa is due to launch on 1 December. Under the scheme, savers will receive up to £3,000 from the government, getting £1 for every £4 they save. Savers will get up to £300 when opening the account, and a monthly bonus of up to £50 (based on a £200 monthly saving).Newcastle Building Society currently offers first-time buyers a two-year tracker mortgage at 1.86% with a £290 valuation fee, a 25-month fixed rate at 1.94%, with a £1,590 valuation fee, or a 25-month fixed rate at 2.27% with a £290 valuation fee. All these loans will revert to a 5.99% standard variable rate after the initial period.