0000704207 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundTreasuryMoneyMarketFundRetailComboPRO16Member 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundPremiumPRO11Member 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundTreasuryMoneyMarketFundRetailComboPRO16Member tp1:S000007504Member 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundTreasuryMoneyMarketFundRetailComboPRO16Member tp1:S000007504Member tp1:C000020481Member 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundPremiumPRO11Member tp1:S000007504Member 2021-12-30 2021-12-30 0000704207 tp1:D1031FidelityTaxExemptMoneyMarketFundPremiumPRO11Member tp1:S000007504Member tp1:C000154297Member 2021-12-30 2021-12-30 iso4217:USD pure 497 2021-10-31 false 0000704207 N-1A Fidelity Newbury Street Trust Supplement to theFidelity® Tax-Exempt Money Market Fund and Fidelity® Treasury Money Market FundDecember 30, 2021Prospectus  Annual Operating Expenses (expenses that you pay each year as a % of the value of your investment) 0.0025 0 0.0022 0.0047 -0.0005 0.0042 February 29, 2024 This example helps compare the cost of investing in the fund with the cost of investing in other funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated: 43 142 255 583 Supplement to theFidelity® Tax-Exempt Money Market FundPremium ClassDecember 30, 2021Prospectus  Annual Operating Expenses (expenses that you pay each year as a % of the value of your investment) 0.0025 0 0.0012 0.0037 -0.0007 0.0030 February 29, 2024 This example helps compare the cost of investing in the fund with the cost of investing in other funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated: 31 107 196 456 (a)Fidelity Management & Research Company LLC (FMR) has contractually agreed to reimburse the class of shares of the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, extraordinary expenses, and acquired fund fees and expenses (including fees and expenses associated with a wholly owned subsidiary), if any, as well as non-operating expenses such as brokerage commissions and fees and expenses associated with the fund's securities lending program, if applicable), as a percentage of its average net assets, exceed 0.42% (the Expense Cap). If at any time during the current fiscal year expenses for the class of shares of the fund fall below the Expense Cap, FMR reserves the right to recoup through the end of the fiscal year any expenses that were reimbursed during the current fiscal year up to, but not in excess of, the Expense Cap. This arrangement will remain in effect through February 29, 2024. FMR may not terminate this arrangement before the expiration date without the approval of the Board of Trustees and may extend it in its discretion after that date. (b)In order to avoid a negative yield, Fidelity Management & Research Company LLC (FMR) may reimburse expenses or waive fees of Fidelity® Tax-Exempt Money Market Fund. Any such waivers or expense reimbursement would be voluntary and could be discontinued at any time. There is no guarantee that Fidelity® Tax-Exempt Money Market Fund will be able to avoid a negative yield. (a)Fidelity Management & Research Company LLC (FMR) has contractually agreed to reimburse Premium Class of the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, extraordinary expenses, and acquired fund fees and expenses (including fees and expenses associated with a wholly owned subsidiary), if any, as well as non-operating expenses such as brokerage commissions and fees and expenses associated with the fund's securities lending program, if applicable), as a percentage of its average net assets, exceed 0.30% (the Expense Cap). If at any time during the current fiscal year expenses for Premium Class of the fund fall below the Expense Cap, FMR reserves the right to recoup through the end of the fiscal year any expenses that were reimbursed during the current fiscal year up to, but not in excess of, the Expense Cap. This arrangement will remain in effect through February 29, 2024. FMR may not terminate this arrangement before the expiration date without the approval of the Board of Trustees and may extend it in its discretion after that date. (b)In order to avoid a negative yield, Fidelity Management & Research Company LLC (FMR) may reimburse expenses or waive fees of Premium Class of the fund. Any such waivers or expense reimbursement would be voluntary and could be discontinued at any time. There is no guarantee that Premium Class or the fund will be able to avoid a negative yield.