Day Count Calculator

This calculator handles the date math behind compliance deadlines. It has two modes, selected with the tabs above the form.

1. Add or Subtract Days: pick a start date (today is preselected), choose a number of days, and choose whether to count after or before the start date. The resulting date appears instantly.
2. Days Between Dates: pick any two dates to see how many calendar days separate them. The order of the dates does not matter.
3. Certification Timeline: choose the certification type, enter the effective date (and the move-in date for a recertification), and optionally list each verification document with its date. The tool builds every related deadline at once and flags documents outside the verification window. Print it as a checklist for the tenant file.

• Earliest acceptable document date: enter the certification effective date, select 120 days, and choose Before. Verifications dated on or after the result are within the window.
• How long a verification stays usable: enter the document date, select 120 days, and choose After. The result is the last effective date the document supports.
• Checking a document's age: use Days Between Dates with the document date and the planned effective date. If the count exceeds 120, the verification is too old.
• The preset chips cover other common windows (45, 90, and 180 days); use the custom field for anything else.

• All counts use calendar days, including weekends and holidays.
• The start date is day zero: one day after January 1 is January 2.
• Leap years and month lengths are handled automatically.
• Counting conventions can differ by program and agency. Confirm the applicable rule with your state agency or investor before relying on a computed deadline.