December 1 – EmployersDuring December, ask employees whose withholding allowances will be different in 2022 to fill out a new Form W4 or Form W4(SP). December 15 – Social Security, Medicare and Withheld Income Tax If the monthly deposit rule applies, deposit the tax for payments in November.December 15 – Nonpayroll Withholding If the monthly deposit rule applies, deposit the tax for payments in November.December 15 – Corporations The fourth installment of estimated tax for 2021 calendar year corporations is due. December 31 – Delayed Payment of Employer Payroll Taxes from 2020If you as an employer delayed paying 2020 payroll taxes under the CARES Act provision, 50% of your share of the 2020 Social Security tax is due by December 31, 2021, and the remainder is due by December 31, 2022. Any payments or deposits you make before December 31, 2021, are first applied against your payment due on December 31, 2021, and then applied against your payment due on December 31, 2022. December 31 – Last Day to Set Up a Keogh Account for 2021If you are self-employed, December 31 is the last day to set up a Keogh Retirement Account if you plan to make a 2021 contribution. If the institution where you plan to set up the account will not be open for business on the 31st, you will need to establish the plan before the 31st. Note: there are other options such as SEP plans that can be set up after the close of the year. Please call the office to discuss your options.December 31 – Caution! Last Day of the Year If the actions you wish to take cannot be completed on the 31st or a single day, you should consider taking action earlier than December 31st.