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addMonths() : Add Months to Date

Add months to a date. Use negative values to subtract months.

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addMonths(date, months)

Parameters

Parameter Type Required Description
date DateTime Yes The date to modify
months Number Yes Number of months to add (can be negative)

Returns

Type: DateTime

A new DateTime with the specified months added.

Examples

Add Months

<p>Due Date: {{format(addMonths(model.startDate, 3), 'MMMM dd, yyyy')}}</p>

Data:

doc.Params["model"] = new {
    startDate = new DateTime(2024, 3, 15)
};

Output:

<p>Due Date: June 15, 2024</p>

Subtract Months

<p>3 months ago: {{format(addMonths(model.today, -3), 'yyyy-MM-dd')}}</p>

Data:

doc.Params["model"] = new {
    today = new DateTime(2024, 3, 15)
};

Output:

<p>3 months ago: 2023-12-15</p>

Payment Schedule

{{#each model.payments}}
  <li>Payment {{add(@index, 1)}}: {{format(addMonths(model.startDate, @index), 'MMM dd, yyyy')}}</li>
{{/each}}

Data:

doc.Params["model"] = new {
    startDate = new DateTime(2024, 1, 15),
    payments = new[] { 1, 2, 3, 4, 5, 6 }
};

Output:

<li>Payment 1: Jan 15, 2024</li>
<li>Payment 2: Feb 15, 2024</li>
<li>Payment 3: Mar 15, 2024</li>
<li>Payment 4: Apr 15, 2024</li>
<li>Payment 5: May 15, 2024</li>
<li>Payment 6: Jun 15, 2024</li>

Annual Review Date

<p>Next Review: {{format(addMonths(model.lastReview, 12), 'MMMM dd, yyyy')}}</p>

Notes

  • Input date is not modified (returns new date)
  • Can add positive or negative months
  • Handles year boundaries automatically
  • If resulting day doesn’t exist (e.g., Feb 31), adjusts to last valid day
  • Use addYears() for year increments
  • Use addDays() for day increments

See Also