Your FHSA carryforward:

• is not your unused FHSA contributions,
• nor is it your unused FHSA participation room.

Your FHSA carryforward is calculated for a year; the definition is extremely confusing and references "year" and "prior year" so we're going to use 2025 as the "particular year".

Your FHSA carryforward for 2025 is the least of:

1. $8,000,
2. The result [A - B], where:

   • A: is the amount determined under paragraph (b) of the annual FHSA limit definition for 2024, minus
   • B: is the result of the amount determined under paragraph (a) of the annual FHSA limit definition for 2024 plus all contributions made to your FHSAs in 2024 after your first qualifying withdrawal
3. $0, if you opened your very first FHSA in 2025 .

Annual FHSA limit calculation for 2024:

Paragraph (a):

• all of your contributions to your FHSAs made in 2024 (except contributions you made after your first qualifying withdrawal)
• plus one of the following amounts:

  • $0 if you opened your first FHSA in 2024, or
  • your amount from paragraph (a) for 2023 that exceeds your annual FHSA limit for 2023
• minus amount of all your designated withdrawals from your FHSAs in 2024 that exceeds your total contributions after your first qualifying withdrawal

Paragraph (b) of the annual FHSA limit definition:

• $8,000
• plus your FHSA carryforward for 2024
• minus the result of the [A - B], where:

  • A: is the sum of all your RRSP to FHSA transfers for 2024 and all earlier years minus all your designated transfers 2024 plus all previous years
  • B: is the sum of all amounts, one for each of 2023 and earlier, determined as follows:

    • $0 if you opened your first FHSA in that year,
    • the lesser of the following amounts:

      • The amount from A for that year minus the amount from B for that year,
      • $8,000 plus your FHSA carryforward for that year.

The CRA's website goes into more detail and provides several examples.